Use common code blocks throughout the entire CE-to-EE docs

doc/update/9.0-ce-to-ee.md

@@ -18,7 +18,9 @@ privileges to the GitLab user on the database version.
 
 ### 1. Stop server
 
-    sudo service gitlab stop
+```bash
+sudo service gitlab stop
+```
 
 ### 2. Get the EE code
 
@@ -48,18 +50,24 @@ sudo -u git -H bundle exec rake assets:clean assets:precompile cache:clear RAILS
 
 ### 4. Start application
 
-    sudo service gitlab start
-    sudo service nginx restart
+```bash
+sudo service gitlab start
+sudo service nginx restart
+```
 
 ### 5. Check application status
 
 Check if GitLab and its environment are configured correctly:
 
-    sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production
+```bash
+sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production
+```
 
 To make sure you didn't miss anything run a more thorough check with:
 
-    sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production
+```bash
+sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production
+```
 
 If all items are green, then congratulations upgrade complete!