Add a note about the /status/ path for load balancers to setup docs

Summary: Fixes T12926. This exists but isn't documented. Document it after the section about webserver setup, since that's probably when you'd want to set it up.

Test Plan: Read carefully, visited `/status/`.

Reviewers: chad, amckinley

Reviewed By: chad

Maniphest Tasks: T12926

Differential Revision: https://secure.phabricator.com/D18234

src/docs/user/configuration/configuration_guide.diviner

@@ -143,6 +143,14 @@ Finally, you should run the following commands to enable php support:
 
 Restart lighttpd after making your edits, then continue below.
 
+
+Load Balancer Health Checks
+===========================
+
+If you're using a load balancer in front of your webserver, you can configure
+it to perform health checks using the path `/status/`.
+
+
 = Setup =
 
 Now, navigate to whichever subdomain you set up. You should see instructions to