More fixes to overview.rst

BUG=None
R=binji@chromium.org

Review URL: https://codereview.chromium.org/24161006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@224815 0039d316-1c4b-4281-b951-d872f2087c98
Update manifest for Chrome Connectivity Diagnostics

BUG=288981
R=dpolukhin@chromium.org

Review URL: https://codereview.chromium.org/24363005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@224816 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 224815
SVN changes up to revision 224816