Also removed part of the message that encourages users to disable updates to
depot_tools. If the users do not enable updates, it prevents landing changes into
project repositories that depend on having latest version of the depot_tools, e.g.
https://codereview.chromium.org/1152823005/.

R=akuegel@chromium.org
TBR=maruel@chromium.org, iannucci@chromium.org
BUG=475320

Review URL: https://codereview.chromium.org/1162153004

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@295486 0039d316-1c4b-4281-b951-d872f2087c98