Update CHANGELOG.md for 11.6.4
Update CHANGELOG.md for 11.6.4

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