Fix Markdown typo in Web IDE docs
Fix Markdown typo in Web IDE docs

As seen in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/5399

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