update migration docs for 8.17 to include minimum node version and yarn installation
update migration docs for 8.17 to include minimum node version and yarn installation

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