revert changes to 8.17 update docs since yarn is now set for 9.0
revert changes to 8.17 update docs since yarn is now set for 9.0

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