Update Markdown validations

.github/workflows/validate_markdown.yml

@@ -12,12 +12,24 @@ jobs:
     - name: Check out code
       uses: actions/checkout@v4.1.0
 
-    # https://github.com/actionshub/markdownlint
+    # https://github.com/marketplace/actions/markdownlint-cli2-action
+    - name: Identify changed files
+      uses: tj-actions/changed-files@v41
+      id: changed-files
+      with:
+        files: '**/*.md'
+        separator: ","
     - name: Markdown Lint
-      uses: actionshub/markdownlint@main
+      uses: DavidAnson/markdownlint-cli2-action@v14
+      if: steps.changed-files.outputs.any_changed == 'true'
+      with:
+        globs: ${{ steps.changed-files.outputs.all_changed_files }}
+        separator: ","
+        config: '.rules/custom.markdownlint.jsonc'
 
     # https://github.com/gaurav-nelson/github-action-markdown-link-check  
     - name: Markdown links
       uses: gaurav-nelson/github-action-markdown-link-check@v1
       with:
         check-modified-files-only: 'yes'
+