style(markdown): drop the comments from the markdownlint config

The header and the rule lists narrated the config instead of being an
exception, a parameter doc or a nocheck directive, and one of them was
wrong: it listed MD040 as kept on while the config disables it. No key
or value changes.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

.markdownlint-cli2.jsonc

@@ -1,17 +1,7 @@
 {
-  // markdownlint-cli2 config — see https://github.com/DavidAnson/markdownlint-cli2
-  // Strategy: keep semantic rules, drop cosmetic ones that would generate
-  // hundreds of baseline findings on the existing tree. Tighten later by
-  // removing entries from the disabled list.
   "config": {
     "default": true,
     "MD004": { "style": "dash" },
-    // Hard-fail rules we keep on:
-    //   MD025 (single H1), MD041 (first line H1), MD026 (no trailing
-    //   heading punctuation), MD034 (no bare URLs), MD040 (fenced code
-    //   language) — all match our documentation.md / readme_md.md.
-    //
-    // Rules disabled for the initial baseline:
     "MD013": false,
     "MD007": false,
     "MD024": { "siblings_only": true },