Run markdownlint before Nanoc checks
Run markdownlint before Nanoc checks

Make it simpler to run markdownlint by moving it before
we do those hacks to run Nanoc.

stoplightio/gitlabhq,mmkassem/gitlabhq,mmkassem/gitlabhq,mmkassem/gitlabhq,stoplightio/gitlabhq,stoplightio/gitlabhq,mmkassem/gitlabhq,stoplightio/gitlabhq