Revert "Edits needed for PostGis addition"

This reverts commit 1aa76a1.

product_docs/docs/biganimal/release/using_cluster/extensions.mdx

@@ -42,7 +42,6 @@ PostgreSQL contrib extensions/modules:
 - pglogical3 (PostgreSQL v12 and v13 only)
 - pgrowlocks
 - pgstattupple
-- postgis
 - postgres_fdw
 - seg (PostgreSQL v12 only)
 - sslinfo
@@ -70,7 +69,7 @@ EDB extensions:
 
 ## Installing extensions
 
-Use the [`CREATE EXTENSION`](https://www.postgresql.org/docs/current/sql-createextension.html) command to install most extensions. You must enable certain extensions, including the EDB Postgres Tuner (pg_tuner) extension and PostGIS on the **DB Configuration** tab of the Create or Edit Cluster page of the BigAnimal portal.
+Use the [`CREATE EXTENSION`](https://www.postgresql.org/docs/current/sql-createextension.html) command to install extensions, except for the EDB Postgres Tuner (pg_tuner) extension. You enable edb_pg_tuner on the **DB Configuration** tab of the Create or Edit Cluster page of the BigAnimal portal.
 
 
 ### Example: Installing multiple extensions