Add a note about merge conflicts in `gitlab.pot`

doc/development/i18n/externalization.md

@@ -124,6 +124,9 @@ strings and remove any strings that aren't used anymore. You should check this
 file in. Once the changes are on master, they will be picked up by
 [Crowdin](http://translate.gitlab.com) and be presented for translation.
 
+If there are merge conflicts in the `gitlab.pot` file, you can delete the file
+and regenerate it using the same command. Confirm that you are not deleting any strings accidentally by looking over the diff.
+
 The command also updates the translation files for each language: `locale/*/gitlab.po`
 These changes can be discarded, the languange files will be updated by Crowdin
 automatically.