docs: fix stale README + help file (audit)

A three-agent audit cross-checked README.md and doc/nuwiki.txt against the
actual config, commands, and mappings in code. Fixes:

Mappings:
- doc/nuwiki.txt wrongly described <Leader>ww as "open today's diary" — it
  opens the wiki index (diary-today is <Leader>w<Leader>w). Corrected, and
  the missing <Leader>wt (wiki index in a tab) row added.
- README feature bullet referenced <Leader>ww for the diary; fixed to
  <Leader>w<Leader>w.
- Both keymap listings now note <Leader>w is the default map_prefix.

Config globals:
- README globals table was missing real, code-read globals: g:nuwiki_syntax,
  g:nuwiki_diary_rel_path, g:nuwiki_wikis, g:nuwiki_map_prefix,
  g:nuwiki_binary_path, g:nuwiki_build_from_source. Added.
- doc/nuwiki.txt globals section gained g:nuwiki_diary_rel_path and
  g:nuwiki_link_severity (both read in autoload but undocumented).
- doc/nuwiki.txt per-wiki list gained template_date_format,
  html_filename_parameterization, color_dic, list_margin (in README only).

Commands:
- doc/nuwiki.txt was missing a whole list/task/table command group plus
  :NuwikiFindOrphans, :NuwikiNormalizeLink, :NuwikiColorize,
  :NuwikiPasteLink/PasteUrl/CatUrl. Added, matching README's descriptions.

No default-value mismatches and no phantom (documented-but-nonexistent)
entries were found. helptags validates with no duplicate tags.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

doc/nuwiki.txt

@@ -201,7 +201,11 @@ match upstream vimwiki.
 `template_path`          Path holding `<name>.tpl` templates.
 `template_default`       `'default'`
 `template_ext`           `'.tpl'`
+`template_date_format`   `'%Y-%m-%d'` — strftime format for `%date` in templates.
 `css_name`               `'style.css'`
+`html_filename_parameterization` `false` — encode subdir paths into the HTML
+                         filename instead of nesting directories.
+`color_dic`              `{}` — map of `{ name = 'color' }` for `:NuwikiColorize`.
 `custom_wiki2html`       `''` — external converter command. When set, export
                          shells out to it instead of the built-in renderer,
                          called as: <cmd> <force> <syntax> <ext> <out_dir>
@@ -227,6 +231,8 @@ match upstream vimwiki.
 `listsyms`               `' .oOX'` — checkbox progression characters.
 `listsym_rejected`       `'-'` — glyph for a cancelled checkbox `[-]`.
 `listsyms_propagate`     `true`
+`list_margin`            `-1` — spaces before a list bullet; `-1` follows
+                         `shiftwidth`.
 `links_space_char`       `' '`
 
 Code fences tagged with a language (`{{{python …}}}`) are highlighted with
@@ -234,6 +240,16 @@ that language's syntax automatically — there is no `nested_syntaxes` key.
 
 Vim-specific globals ~
 
+                                                     *g:nuwiki_diary_rel_path*
+`g:nuwiki_diary_rel_path`      `'diary'`
+    Diary subdirectory, relative to the wiki root. The scalar form for the
+    single-wiki shape; per-wiki `diary_rel_path` (or `g:nuwiki_wikis`) wins.
+
+                                                      *g:nuwiki_link_severity*
+`g:nuwiki_link_severity`       `'warn'`
+    Broken-link diagnostic severity: `off` | `hint` | `warn` | `error`. The
+    scalar/global form of the `diagnostic.link_severity` setup() option.
+
                                                   *g:nuwiki_no_default_mappings*
 `g:nuwiki_no_default_mappings` 0
     When 1, the Vim path skips every buffer-local keymap. Equivalent to
@@ -417,6 +433,15 @@ Page generation ~
     range (e.g. `:'<,'>NuwikiCheckLinks`) the report is limited to the current
     buffer's selected lines.
 
+                                                         *:NuwikiFindOrphans*
+:NuwikiFindOrphans
+    List pages with no incoming links in the |quickfix| list.
+
+                                                       *:NuwikiNormalizeLink*
+:NuwikiNormalizeLink [0|1]
+    Turn the word (or, with arg `1`, the visual selection) under the cursor
+    into a wikilink. Backs the `+` mapping.
+
 Tags ~
 
                                                           *:NuwikiSearchTags*
@@ -451,8 +476,86 @@ HTML export ~
 :NuwikiRss
     Write `rss.xml` summarising recent diary entries.
 
+Lists, tasks & tables ~
+
+                                                             *:NuwikiNextTask*
+:NuwikiNextTask
+    Jump to the next unfinished task in the buffer.
+
+                                                         *:NuwikiListToggle*
+:NuwikiListToggle
+    Toggle a checkbox on the current item, adding `[ ]` if it has none.
+
+                                                      *:NuwikiToggleListItem*
+:[range]NuwikiToggleListItem
+    Toggle the checkbox under the cursor. With a range, every item in the
+    selection.
+
+                                                       *:NuwikiToggleRejected*
+:NuwikiToggleRejected
+    Toggle the rejected marker `[-]` on the current item.
+
+                                  *:NuwikiIncrementListItem* *:NuwikiDecrementListItem*
+:[range]NuwikiIncrementListItem
+:[range]NuwikiDecrementListItem
+    Cycle the current item's list marker to the next / previous symbol.
+    With a range, every item in the selection.
+
+                                  *:NuwikiChangeSymbol* *:NuwikiChangeSymbolInList*
+:NuwikiChangeSymbol {sym}
+:NuwikiChangeSymbolInList {sym}
+    Set the current item's marker to `{sym}` — or every item in the list,
+    for the `InList` form.
+
+                                                         *:NuwikiListChangeLvl*
+:NuwikiListChangeLvl [increase|decrease]
+    Indent (`increase`) or dedent (`decrease`) the current list item.
+
+                                                          *:NuwikiRemoveDone*
+:NuwikiRemoveDone[!]
+    Remove every completed item from the current list; with `!`, from the
+    whole buffer.
+
+                                  *:NuwikiRemoveCheckbox* *:NuwikiRemoveCheckboxInList*
+:[range]NuwikiRemoveCheckbox
+:NuwikiRemoveCheckboxInList
+    Strip the checkbox from the current item (or the range), or from every
+    item in the current list for the `InList` form.
+
+                                  *:NuwikiRenumberList* *:NuwikiRenumberAllLists*
+:NuwikiRenumberList
+:NuwikiRenumberAllLists
+    Renumber the current ordered list, or every ordered list in the buffer.
+
+                                                               *:NuwikiTable*
+:NuwikiTable {cols} [rows]
+    Insert a table with `{cols}` columns (and optional `[rows]`) at the cursor.
+
+                                                          *:NuwikiTableAlign*
+:NuwikiTableAlign
+    Re-align the current table's columns.
+
+                          *:NuwikiTableMoveColumnLeft* *:NuwikiTableMoveColumnRight*
+:NuwikiTableMoveColumnLeft
+:NuwikiTableMoveColumnRight
+    Move the table column under the cursor left / right.
+
 Other ~
 
+                                                            *:NuwikiColorize*
+:[range]NuwikiColorize {color}
+    Wrap the word (or the visual selection) under the cursor in a coloured
+    `<span>`. `{color}` may be a `color_dic` name or a literal CSS colour.
+
+                                       *:NuwikiPasteLink* *:NuwikiPasteUrl*
+:NuwikiPasteLink
+:NuwikiPasteUrl
+    Paste the clipboard contents as a wikilink, or as a raw URL.
+
+                                                              *:NuwikiCatUrl*
+:NuwikiCatUrl
+    Echo the `file://` URL of the current page's HTML export.
+
                                                               *:NuwikiInstall*
 :NuwikiInstall
     Install (or re-install) the `nuwiki-ls` binary into the plugin's
@@ -529,7 +632,11 @@ Tables (normal mode) ~
 
 Wiki / diary / export ~
 
-  <Leader>ww            Open today's diary.
+The `<Leader>w` prefix below is the default |map_prefix| / |g:nuwiki_map_prefix|;
+set that option to relocate the whole family.
+
+  <Leader>ww            Open the wiki index.
+  <Leader>wt            Open the wiki index in a new tab.
   <Leader>ws            Pick a wiki.
   <Leader>wi            Open the diary index.
   <Leader>w<Leader>w    Today.