docs(git): remove stale check-manifests/skill-frontmatter examples

f11b645 and bde9f7f swept check-manifests and skill-frontmatter
references left over from e647f14 and c8a7c9e, but missed two worked
examples in this vendored pre-commit research doc: a "Validate a
generated file" hook naming the deleted scripts/check-manifests.sh,
and a "SKILL.md frontmatter validation (inline bash, as used in this
repo)" example for the skill-frontmatter hook, folded into
skill-size-check.sh in c8a7c9e.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YR2CjVumUbEGWcMikcoXBD

plugins/git/docs/research/docs/pre-commit/examples.md

@@ -157,20 +157,6 @@ pre-commit run --from-ref origin/main --to-ref HEAD
       files: \.env(\..+)?$
 ```
 
-### Validate a generated file
-
-```yaml
-- repo: local
-  hooks:
-    - id: validate-manifest
-      name: Validate plugin manifest
-      entry: bash scripts/check-manifests.sh
-      language: unsupported_script
-      files: ^\.claude-plugin/
-      pass_filenames: false
-      always_run: false
-```
-
 ### Run full test suite pre-push
 
 ```yaml
@@ -185,29 +171,6 @@ pre-commit run --from-ref origin/main --to-ref HEAD
       stages: [pre-push]
 ```
 
-### Validate SKILL.md frontmatter (inline bash, as used in this repo)
-
-```yaml
-- repo: local
-  hooks:
-    - id: skill-frontmatter
-      name: SKILL.md frontmatter validation
-      entry: bash
-      language: system
-      files: 'SKILL\.md$'
-      args:
-        - -c
-        - |
-          for f in "$@"; do
-            if [[ -f "$f" ]]; then
-              if ! grep -q "^name:" "$f" || ! grep -q "^description:" "$f"; then
-                echo "ERROR: $f missing required frontmatter (name: and description:)"
-                exit 1
-              fi
-            fi
-          done
-```
-
 ## Adding meta-validation
 
 Add after all other repos to catch dead hooks/excludes: