chore: tweak layout

Author: tianzhou

content/reference/postgres/how-to/_layout.md

@@ -3,7 +3,7 @@
 
 ## [Overview](/reference/postgres/how-to/overview)
 
-### [Row Level Security (RLS)](/reference/postgres/how-to/overview/postgres-row-level-security)
+## [Row Level Security (RLS)](/reference/postgres/how-to/overview/postgres-row-level-security)
 
 ## [How to check Postgres version](/reference/postgres/how-to/how-to-check-postgres-version)