fix(ci): include all markdown files in lychee link check

Previously, the workflow only checked markdown files in the skills/
directory and the root README.md. This caused failures when PRs
modified markdown files in other directories (e.g., third_party/).

Now all changed markdown files are included in the link check,
regardless of their directory location.

Fixes CI failure in PR #263 where third_party/ElevenLabs/README.md
changes were not being checked.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: zealoushacker

.github/workflows/links.yml

@@ -79,8 +79,8 @@ jobs:
         run: |
           FILES=""
 
-          # Add changed markdown files from skills directory
-          echo "${{ steps.changed-files.outputs.files }}" | grep '^skills/.*\.md$' | while read f; do
+          # Add all changed markdown files (from any directory)
+          echo "${{ steps.changed-files.outputs.files }}" | grep '\.md$' | while read f; do
             if [ -f "$f" ]; then
               FILES="$FILES $f"
             fi
@@ -91,11 +91,6 @@ jobs:
             FILES="$FILES temp_md/*.md"
           fi
 
-          # Add README.md if changed
-          if echo "${{ steps.changed-files.outputs.files }}" | grep -q '^README\.md$'; then
-            FILES="$FILES README.md"
-          fi
-
           # Remove leading/trailing whitespace
           FILES=$(echo $FILES | xargs)