docs: align README and CONTRIBUTING with commit-msg rules

Top-level and contributor README text now mention layout as well as width when
hooks gate commits.

- Note subject and bullet structure in README.md contributing blurb
- Mirror the same requirement in docs/CONTRIBUTING.md Git subsection

README.md

@@ -86,8 +86,8 @@ what you changed.
 **Git commits.** Keep history easy to read: small commits, usually one file;
 **two files** in one commit is fine when they are inseparable (e.g. a helper and
 its only caller). With `.githooks/` and `core.hooksPath`, **pre-commit** caps
-staged paths at two and **commit-msg** rejects log lines longer than **80
-characters** (wrap subject, summary, and bullets). If that workflow feels
+staged paths at two and **commit-msg** enforces subject, summary, `-` bullets,
+and an **80**-character line cap. If that workflow feels
 unfamiliar, open your PR with tests passing and ask for help splitting history
 in review.
 

docs/CONTRIBUTING.md

@@ -65,8 +65,8 @@ when rendering the website) rather than chasing false positives in the library.
   unless you mean it. The full protocol is in
   `.github/prompts/commit.prompt.md`. With
   `git config core.hooksPath .githooks`, **pre-commit** allows at most **two**
-  staged files per commit, and **commit-msg** rejects messages with any line
-  longer than **80 characters** (merge commits skip the length check while
+  staged files per commit, and **commit-msg** enforces the subject / summary /
+  bullet layout plus an **80**-character line cap (merge commits skip while
   `.git/MERGE_HEAD` exists).
 - Match **commit message depth** to the patch: a short summary suffices for
   small edits; **large files, large diffs, or several concerns in one commit**