feat: improve docs

BREAKING CHANGE: trigger major release

Author: hsluoyz

README.md

@@ -8,7 +8,7 @@
 [![Download](https://img.shields.io/pypi/dm/casbin-postgresql-watcher.svg)](https://pypi.org/project/casbin-postgresql-watcher/)
 [![Discord](https://img.shields.io/discord/1022748306096537660?logo=discord&label=discord&color=5865F2)](https://discord.gg/S5UjpzGZjN)
 
-Casbin watcher based on PostgreSQL for monitoring updates to casbin policies
+Casbin watcher based on PostgreSQL for monitoring updates to casbin policies.
 
 ## Installation
 ```bash