Fix PostGIS doc (#30520)

postgis uses `"gis"` schema, thus running the command as it is in the docs leads to an error
`type "geography" does not exist`

prefixing using the schema `gis.geometry` fixes the issue

apps/docs/content/guides/database/extensions/postgis.mdx

@@ -58,7 +58,7 @@ Let’s create our table. Each row represents a restaurant with its location sto
 create table if not exists public.restaurants (
 	id int generated by default as identity primary key,
 	name text not null,
-	location geography(POINT) not null
+	location gis.geography(POINT) not null
 );
 ```