Added note about steps only required for DR Alpha

doc/gitlab-geo/configuration.md

@@ -150,22 +150,26 @@ sensitive data in the database. Any secondary node must have the
     sudo -i
     ```
 
-1. Edit the /etc/gitlab/gitlab.rb:
+1. (This step is required only if you want to enable the new Disaster Recovery
+   feature in Alpha shipped in GitLab 9.0) Edit the /etc/gitlab/gitlab.rb:
 
     ```
     geo_postgresql['enable'] = true
     ```
 
-1. Create `database_geo.yml` with the information of your secondary PostgreSQL
-   database.  Note that GitLab will set up another database instance separate
-   from the primary, since this is where the secondary will track its internal
-   state:
+1. (This step is required only if you want to enable the new Disaster Recovery
+   feature in Alpha shipped in GitLab 9.0) Create `database_geo.yml` with the
+   information of your secondary PostgreSQL database.  Note that GitLab will
+   set up another database instance separate from the primary, since this is
+   where the secondary will track its internal state:
 
     ```
     sudo cp /opt/gitlab/embedded/service/gitlab-rails/config/database_geo.yml.postgresql /opt/gitlab/embedded/service/gitlab-rails/config/database_geo.yml
     ```
 
-1. Edit the content of `database_geo.yml` in `production:` like the example below:
+1. (This step is required only if you want to enable the new Disaster Recovery
+   feature in Alpha shipped in GitLab 9.0) Edit the content of
+   `database_geo.yml` in `production:` like the example below:
 
    ```yaml
    #
@@ -183,13 +187,15 @@ sensitive data in the database. Any secondary node must have the
 
    ```
 
-1. Reconfigure GitLab:
+1. (This step is required only if you want to enable the new Disaster Recovery
+  feature in Alpha shipped in GitLab 9.0) Reconfigure GitLab:
 
     ```
     sudo gitlab-ctl reconfigure
     ```
 
-1. Set up the Geo tracking database:
+1. (This step is required only if you want to enable the new Disaster Recovery
+  feature in Alpha shipped in GitLab 9.0) Set up the Geo tracking database:
 
     ```
     sudo gitlab-rake geo:db:setup