fix: reference crossfilereferenceintegrity helpers by name, not line

Line numbers drift as the file evolves. Replace 'around lines 349 and
389' with a reference to the collectHeadingAnchors / slugify helpers.

Author: claude

plan/89_toc-generator-directive.md

@@ -90,17 +90,17 @@ heading anchor mdsmith already computes for
 cross-file heading references.
 
 Do not define a TOC-specific slug algorithm.
-Reuse the `slugify` function and
+Reuse the `slugify` function and the
 duplicate-disambiguation logic currently in
 [`internal/rules/crossfilereferenceintegrity/rule.go`][cfri]
-(around lines 349 and 389). Move that helper
-into a shared package — `internal/mdtext/` is
-the natural home — and have both rules call
-the shared code so anchors stay consistent
-across rules. Repeated headings must receive
-the same `-1`, `-2`, … suffixes in source
-order as the existing reference-integrity
-rule.
+(used by `collectHeadingAnchors`). Move that
+helper into a shared package —
+`internal/mdtext/` is the natural home — and
+have both rules call the shared code so
+anchors stay consistent across rules. Repeated
+headings must receive the same `-1`, `-2`, …
+suffixes in source order as the existing
+reference-integrity rule.
 
 [cfri]: ../internal/rules/crossfilereferenceintegrity/rule.go