Fix ps invocation in check.rake

'bundle exec rake gitlab:check RAILS_ENV=production' fails on FreeBSD due to ps truncation.  Fix this error and encourage the user to run the check.

doc/install/installation-freebsd.md

@@ -173,6 +173,18 @@ The `secrets.yml` file stores encryption keys for sessions and secure variables.
 Backup `secrets.yml` someplace safe, but don't store it in the same place as your database backups.
 Otherwise your secrets are exposed if one of your backups is compromised.
 
+### Fix Sidekiq Check
+
+The `check.rake` file uses `ps` to check whether or not Sidekiq is running; however, it does not account for column truncation. 
+
+    vi /usr/local/www/gitlab/lib/tasks/gitlab/check.rake
+
+    # Add a 'w' to the ps arguments.  Change this line:
+    #  ps_ux, _ = Gitlab::Popen.popen(%W(ps ux))
+    # to read:
+    #  ps_ux, _ = Gitlab::Popen.popen(%W(ps wux))
+
+
 ### Check Application Status
 
 Check if GitLab and its environment are configured correctly:
@@ -190,6 +202,12 @@ Check if GitLab and its environment are configured correctly:
     # or this:
     /usr/local/etc/rc.d/gitlab restart
 
+### Check Gitlab Status
+
+    su - git
+    cd /usr/local/www/gitlab
+    bundle exec rake gitlab:check RAILS_ENV=production
+
 ## 7. Nginx
 
 **Note:** Nginx is the officially supported web server for GitLab. If you cannot or do not want to use Nginx as your web server, have a look at the [GitLab recipes](https://gitlab.com/gitlab-org/gitlab-recipes/).