Update instructions for creating gh-pages branch
Adding extra icons (ga & snapshot) to download & docs widgets
Merge commit '0fa4ba6591e4d1b1033ce1f7b004539d31266872' into gh-pages

# By Chris Beams (1) and Gonçalo Silva and Nick Street (1)
* commit '0fa4ba6591e4d1b1033ce1f7b004539d31266872':
  Adding extra icons (ga & snapshot) to download & docs widgets
  Update instructions for creating gh-pages branch