CONTRIBUTING: mention comment feature

CONTRIBUTING.md

@@ -20,6 +20,8 @@ before translating a piece of text, check that no one has made a translation yet
 
 if no one has submitted a translation, or the submitted translation seems wrong to you, you can submit your translation by clicking the **Suggest** button for each individual string, which sends it off for human review. we will then check it to to ensure no malicious translations are submitted, and add it to cobalt.
 
+if any translation string's meaning seems unclear to you, please leave a comment on the *Comments* tab, and we will either add an explanation or a screenshot.
+
 ## adding features or support for services
 before putting in the effort to implement a feature, it's worth considering whether it would be appropriate to add it to cobalt. the cobalt api is built to assist people **only with downloading freely accessible content**. other functionality, such as:
 - downloading paid / not publicly accessible content