Adds an extra line to the default text description to help judge whether the
76 character recommended limit is being passed.

Review URL: https://chromiumcodereview.appspot.com/15670012

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@203314 0039d316-1c4b-4281-b951-d872f2087c98