Merge branch 'stable-2.6' into stable-2.7

* stable-2.6:
  Fix spelling errors in access-control.txt
  Access control documentation: Formatting
  Access control documentation: Clean up of categories
  Access Control Documentation: Explain special and magic refs
  Set core plugins to correct revisions for 2.6-rc2
  Update developer instructions for cloning the Gerrit project
  Fix Windows build

Change-Id: Ic6a27ddffed8521f10aaca9ca6619840174be1ff