Updated mediawiki/extensions
Project: mediawiki/extensions/BetaFeatures  98b8fc0c442cb3e88ffbbd37e78880064e9ef52c

Consistency tweaks for translatewiki.net

* Standardize extension description message key
* Rephrase message a bit

PS2: Define messages array

Change-Id: Ie68ad01733984c0712fe4bc77b4b892f10a4d468