Add pre-commit hook for validating release notes

- This is a pre-commit hook using `pre-commit` framework to validate release notes YAML files.
- The hook checks for correct structure, formatting and required fields in the `release-notes` directory.
- This ensures consistency in release notes before committing changes.
- Added release notes validation to the `make syntax-check` target

Ref: #934 (comment)

.pre-commit-config.yaml

@@ -0,0 +1,8 @@
+repos:
+-   repo: local
+    hooks:
+    -   id: validate-release-notes
+        name: Validate Release Notes
+        entry: python ci/check-release-notes.py
+        language: python
+        files: ^release-notes/.*\.yml$

Makefile

@@ -1,7 +1,8 @@
-.PHONY: syntax-check
+.PHONY: syntax-check pre-commit-check print-rollouts
+
 syntax-check:
 	@find streams updates -iname '*.json' | sort | xargs -n 1 python3 -c 'import json, sys; json.load(open(sys.argv[1]))'
+	@python ci/check-release-notes.py release-notes/*.yml
 
-.PHONY: print-rollouts
 print-rollouts:
 	@find updates -iname '*.json' -printf '%f\n' | cut -f1 -d. | sort | xargs ./rollout.py print