docs(config): drop client-side keys and refresh per-wiki reference

Remove nested_syntaxes, maxhi and diary_start_week_day from the config
reference (block, tables and key lists) since the server no longer
consumes them, and note that language-tagged code fences are highlighted
automatically with no nested_syntaxes key.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

development/SPEC.md

@@ -236,9 +236,9 @@ require('nuwiki').setup({
 ```
 
 Per-wiki keys include `index`, `diary_rel_path`/`diary_index`/
-`diary_frequency`/`diary_start_week_day`/`diary_sort`/`diary_caption_level`/
+`diary_frequency`/`diary_sort`/`diary_caption_level`/
 `diary_header`, `listsyms`/`listsyms_propagate`/`list_margin`,
-`links_space_char`, `nested_syntaxes`, `auto_toc`, `maxhi`, and an `html`
+`links_space_char`, `auto_toc`, and an `html`
 table (`html_path`, `template_path`/`template_default`/`template_ext`/
 `template_date_format`, `css_name`, `auto_export`,
 `html_filename_parameterization`, `exclude_files`, `color_dic`).