Docs: Add TZInfo formatted timezones

doc/workflow/timezone.md

 # Changing your time zone
 
 The global time zone configuration parameter can be changed in `config/gitlab.yml`:
+
 ```
-    # time_zone: 'UTC'
+# time_zone: 'UTC'
 ```
 
-Uncomment and customize if you want to change the default time zone of GitLab application.
+Uncomment and customize if you want to change the default time zone of the GitLab application.
+
+
+## Viewing available timezones
 
 To see all available time zones, run `bundle exec rake time:zones:all`.
 
-With Omnibus installations, run `gitlab-rake time:zones:all`.
+For Omnibus installations, run `gitlab-rake time:zones:all`.
+
+NOTE: **Note:**
+Currently, this rake task does not list timezones in TZInfo format required by GitLab Omnibus during a reconfigure: [#58672](https://gitlab.com/gitlab-org/gitlab-ce/issues/58672).
 
 ## Changing time zone in omnibus installations
 
 GitLab defaults its time zone to UTC. It has a global timezone configuration parameter in `/etc/gitlab/gitlab.rb`.
 
-To update, add the time zone that best applies to your location. Here are two examples:
+To obtain a list of timezones, log in to your GitLab application server and run a command that generates a list of timezones in TZInfo format for the server. For example, install `timedatectl` and run `timedatectl list-timezones`.
+
+To update, add the timezone that best applies to your location. For example:
+
 ```
 gitlab_rails['time_zone'] = 'America/New_York'
 ```
-or
-```
-gitlab_rails['time_zone'] = 'Europe/Brussels'
-```
 
-After you added this field, reconfigure and restart:
+After adding the configuration parameter, reconfigure and restart your GitLab instance:
+
 ```
 gitlab-ctl reconfigure
 gitlab-ctl restart
 ```
+