Merge branch '32881-aqualls-enable-rule-MD040' into 'master'

Enable markdownlint rule MD040

Closes #32881

See merge request gitlab-org/gitlab!27940

.markdownlint.json

@@ -22,7 +22,6 @@
     "style": "---"
   },
   "no-emphasis-as-heading": false,
-  "fenced-code-language": false,
   "first-line-h1": false,
   "code-block-style": {
     "style": "fenced"