Update CHANGELOG.md for 8.16.5
Update CHANGELOG.md for 8.16.5

[ci skip]
darkrasid/gitlabhq,darkrasid/gitlabhq,jirutka/gitlabhq,iiet/iiet-git,t-zuehlsdorff/gitlabhq,LUMC/gitlabhq,htve/GitlabForChinese,dreampet/gitlab,LUMC/gitlabhq,darkrasid/gitlabhq,dreampet/gitlab,mmkassem/gitlabhq,htve/GitlabForChinese,LUMC/gitlabhq,dplarson/gitlabhq,axilleas/gitlabhq,axilleas/gitlabhq,stoplightio/gitlabhq,jirutka/gitlabhq,jirutka/gitlabhq,htve/GitlabForChinese,htve/GitlabForChinese,mmkassem/gitlabhq,dplarson/gitlabhq,iiet/iiet-git,LUMC/gitlabhq,axilleas/gitlabhq,axilleas/gitlabhq,t-zuehlsdorff/gitlabhq,dplarson/gitlabhq,dreampet/gitlab,mmkassem/gitlabhq,iiet/iiet-git,darkrasid/gitlabhq,stoplightio/gitlabhq,dplarson/gitlabhq,mmkassem/gitlabhq,iiet/iiet-git,t-zuehlsdorff/gitlabhq,stoplightio/gitlabhq,jirutka/gitlabhq,dreampet/gitlab,stoplightio/gitlabhq,t-zuehlsdorff/gitlabhq