Update labeler workflow (#4023)

.github/labeler.yml

@@ -1,11 +1,18 @@
 # Add Documentation tag to PR's changing markdown files, or anything in the docs folder
-Documentation:
+'pr: documentation':
 - changed-files:
   - any-glob-to-any-file:
       - docs/*
       - '**/*.md'
 
 # Add Haxe tag to PR's changing haxe code files
-Haxe:
+'pr: haxe':
 - changed-files:
   - any-glob-to-any-file: '**/*.hx'
+
+# Add GitHub tag to PR's changing yml files, or anything in the .github folder 
+'pr: github':
+- changed-files:
+  - any-glob-to-any-file:
+      - github/*
+      - '**/*.yml'