Update CHANGELOG.md for 11.3.6
Update CHANGELOG.md for 11.3.6

[ci skip]
dreampet/gitlab,dreampet/gitlab,mmkassem/gitlabhq,iiet/iiet-git,axilleas/gitlabhq,mmkassem/gitlabhq,iiet/iiet-git,axilleas/gitlabhq,stoplightio/gitlabhq,dreampet/gitlab,mmkassem/gitlabhq,stoplightio/gitlabhq,axilleas/gitlabhq,dreampet/gitlab,iiet/iiet-git,iiet/iiet-git,mmkassem/gitlabhq,stoplightio/gitlabhq,stoplightio/gitlabhq,axilleas/gitlabhq