feat: adjust postgres-create-user.md

doc/postgres-create-user.md

@@ -11,6 +11,11 @@ CREATE USER <user name> with encrypted password '<key>';
 grant all privileges on database <database name> to <user name>;
 ```
 
+* OPTION: add all privileges for a <schema name> to a <user>
+```
+GRANT ALL ON SCHEMA <schema name> TO <user name>;
+```
+
 * OPTION: if <user name> already exist, pw can be changed this way
 ```
 ALTER USER <user name> WITH ENCRYPTED PASSWORD '<key>';