Update installing-redisgears.md

Adding directions on how to use the newly installed redisgears version to upgrade a database. 
It was a little jarring not having this available on this page. It left me hanging when I needed to upgrade a database. It took me a good five minutes to fine the information on how to apply the upgrade to a database.

Author: JeffreyGroves

content/operate/oss_and_stack/stack-with-enterprise/gears-v1/installing-redisgears.md

@@ -85,3 +85,14 @@ After installation, create a new database and enable RedisGears:
 ## Uninstall RedisGears
 
 To uninstall RedisGears, make a [`DELETE` request to the `/v2/modules` REST API endpoint]({{< relref "/operate/rs/references/rest-api/requests/modules#delete-module-v2" >}}).
+
+## Upgrade existing databases to a new version of RedisGear
+
+To upgrade an existing database, use the following `rladmin` command:
+   ```sh
+   rladmin upgrade db <database-name-or-ID> and module module_name rg version <new_version_integer> module_args "<module arguments>"
+   ```
+Example: To upgrade database `shoppingcart` to RedisGears version 1.2.9 and to continue to use the same configuration:
+   ```sh
+   rladmin upgrade db shopping-cart and module module_name rg version 10209 module_args keep_args
+   ```