Fix double colons in api help output

  Get links from the [[Main Page]]::
    api.php?action=query&prop=links&titles=Main%20Page
  Get information about the link pages in the [[Main Page]]::
    api.php?action=query&generator=links&titles=Main%20Page&prop=info
  Get links from the Main Page in the User and Template namespaces::
    api.php?action=query&prop=links&titles=Main%20Page&plnamespace=2|10

Change-Id: I3645bd72d80aef3f99da7f8f5fa1d63a1b28ad78
Merge "Fix double colons in api help output"