build: add root documentation files to labeler config (#6550)

Signed-off-by: Ayush More <ayushmore42595@gmail.com>

Author: Ayushmore1214

.github/labeler.yaml

@@ -21,6 +21,9 @@ area/manifests:
 area/docs:
 - docs/*
 - docs/**/*
+- README.md
+- CONTRIBUTING.md
+- RELEASES.md
 
 area/examples:
 - examples/*