change domain to hostname in usage ping doc
change domain to hostname in usage ping doc

t-zuehlsdorff/gitlabhq,iiet/iiet-git,mmkassem/gitlabhq,stoplightio/gitlabhq,dreampet/gitlab,t-zuehlsdorff/gitlabhq,stoplightio/gitlabhq,iiet/iiet-git,axilleas/gitlabhq,jirutka/gitlabhq,mmkassem/gitlabhq,dplarson/gitlabhq,t-zuehlsdorff/gitlabhq,dplarson/gitlabhq,jirutka/gitlabhq,dreampet/gitlab,dreampet/gitlab,axilleas/gitlabhq,jirutka/gitlabhq,t-zuehlsdorff/gitlabhq,dplarson/gitlabhq,iiet/iiet-git,stoplightio/gitlabhq,iiet/iiet-git,mmkassem/gitlabhq,dplarson/gitlabhq,axilleas/gitlabhq,dreampet/gitlab,mmkassem/gitlabhq,jirutka/gitlabhq,stoplightio/gitlabhq,axilleas/gitlabhq