Merge pull request #20920 from Homebrew/rubocop-md-ignore-copilot-instructions-file

rubocop: Ignore `.github/copilot-instructions.md` under `AllCops`

Author: p-linnane

Library/.rubocop.yml

@@ -31,6 +31,7 @@ AllCops:
     - "Homebrew/bin/*"
     - "Homebrew/vendor/**/*"
     - "Taps/*/*/vendor/**/*"
+    - "**/.github/copilot-instructions.md" # This should be treated the same as the `docs/` files.
   SuggestExtensions:
     rubocop-minitest: false