Additional fixes to new notification docs

Implemented as many of Mike's comments in cl: https://codereview.chromium.org/12315133/
that I could, without breaking build before api moves out of experimental officially.

Also changed name of notifications.html docs to desktop_notifications and corrected
navigation to new docs both for extensions and apps.

This is in preparation for new api moving out of experimental and being named 'notifications'.

NOTRY=TRUE

Review URL: https://chromiumcodereview.appspot.com/12497004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@186368 0039d316-1c4b-4281-b951-d872f2087c98
8 files changed