Update patch_versions.md, add `yarn:install` in `Clean up assets and cache` command.

doc/update/patch_versions.md

@@ -57,7 +57,7 @@ sudo -u git -H bundle clean
 sudo -u git -H bundle exec rake db:migrate RAILS_ENV=production
 # Clean up assets and cache
-sudo -u git -H bundle exec rake gitlab:assets:clean gitlab:assets:compile cache:clear RAILS_ENV=production
+sudo -u git -H bundle exec rake yarn:install gitlab:assets:clean gitlab:assets:compile cache:clear RAILS_ENV=production
 ```
 ### 4. Update gitlab-workhorse to the corresponding version