Fix variable number in message

Per message doc:
$1 is the user who performed the action
$10 is the number of notified languages

Spotted by Pikne
https://translatewiki.net/wiki/Thread:Translating_talk:MediaWiki/About_MediaWiki:Logentry-translationnotifications-sent/en

Change-Id: Idc7b7a1987b54ffbc1de479628830466fc19dd05