[WikiGrok] Register extension. Was deployed to WMF cluster too

https://git.wikimedia.org/commitdiff/operations%2Fmediawiki-config/a0127a1fac55e1a30ecf16c2cc12784343876046

Change-Id: Ib1b966187d5ede4c0b762557a8fe0a5054d5e5dd