Fix i18n issues.

Issues discovered after some questions were asked by Shirayuki at:
* https://translatewiki.net/wiki/Thread:Support/About_MediaWiki:Articlefeedbackv5-form-helpful-votes/en
* https://translatewiki.net/wiki/Thread:Support/About_MediaWiki:Articlefeedbackv5-percent-found/en_%283%29

Change-Id: Ib8c008888a86827f2fe2f0ad6a7fad328a39da75