feat: docs reference generates a skill catalogue and a page-type reference under docs/reference/ from the shipped defaults, checked and written in the origin repo only (#189)

Files changed:
- CHANGES.md
- README.md
- VERSION
- docs/reference/README.md
- docs/reference/commands/README.md
- docs/reference/commands/types-instructions-and-docs.md
- docs/reference/page-types.md
- docs/reference/skills.md
- instructions/dev/doc-pull-through.md
- tools/CONTRACT.md
- tools/README.md
- tools/chemenu/commands/docs_verify.py
- tools/chemenu/reference_doc.py
- tools/chemenu/tests/test_reference_doc.py

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SnAJ7Z3CpVD3PRbN73QtU2

docs/reference/README.md

@@ -9,6 +9,11 @@ written by hand.
   generated from the same records as `tools/wikitool <command> -h`.
 - [Exit codes and gates](exit-codes.md) - which commands can stop and wait for a person, and
   why.
+- [Skill catalogue](skills.md) - the skills the stack ships, what each does and which requests
+  start it, generated from their `SKILL.md`.
+- [Page types](page-types.md) - every page type the stack ships for `kb/`, its subtypes, where
+  its pages are written and its required fields, generated from the type-specs.
 
-Page types are not generated here yet; until they are, a page type is described by
-`tools/wikitool types describe <type>`.
+The last two describe the stack's shipped defaults, which an instance may change or extend;
+`tools/wikitool instructions list` and `tools/wikitool types describe <type>` show what one
+instance has.