removed extra h2 markdown symbol
Merge pull request #2340 from tysonn/master

Moving metadata guidance to external contributors guide
Added list for tags section
www.windowsazure.com -> azure.microsoft.com
Merge pull request #2339 from DavidHoerster/fixTitle

removed extra h2 markdown symbol
Merge pull request #2342 from dabutvin/patch-16

www.windowsazure.com -> azure.microsoft.com
metadata article updates