Updated mediawiki/extensions
Project: mediawiki/extensions/E3Experiments  17e8e07a57ca9dc2a7d3fa02affe5d6b4349aaae

Consistency tweak in preparation for adding extension to translatewiki.net

* Remove 'experiments' message. Seems unused
* Sync extensions description message key with extension name
* Add message documentation
* Fix type of extension: It's not a special page

Change-Id: I3d570e8c581c64b165e5980e888eef13e8c09cca