[Content Linter Rule] Third Party Action References Must Use SHA (#52282)

Co-authored-by: Rachael Sewell <rachmari@github.com>
Co-authored-by: Ben Ahmady <32935794+subatoi@users.noreply.github.com>
Co-authored-by: Felicity Chapman <felicitymay@github.com>

src/content-linter/style/github-docs.js

@@ -155,6 +155,12 @@ const githubDocsConfig = {
     severity: 'error',
     'partial-markdown-files': true,
   },
+  'third-party-action-pinning': {
+    // GH041
+    severity: 'error',
+    'partial-markdown-files': true,
+    'yml-files': true,
+  },
 }
 
 export const githubDocsFrontmatterConfig = {