[Release tools] Add instructions how to close the auto-roller.

tools/release/chromium_roll.py

 #!/usr/bin/env python
 # Copyright 2014 the V8 project authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import argparse
 import os
 import sys
 
 from common_includes import *
 
-
 ROLL_SUMMARY = ("Summary of changes available at:\n"
                 "https://chromium.googlesource.com/v8/v8/+log/%s..%s")
 
-
 ISSUE_MSG = (
 """Please follow these instructions for assigning/CC'ing issues:
-https://code.google.com/p/v8-wiki/wiki/TriagingIssues""")
+https://code.google.com/p/v8-wiki/wiki/TriagingIssues
+
+Please close rolling in case of a roll revert:
+https://v8-roll.appspot.com/""")
 
 class Preparation(Step):
   MESSAGE = "Preparation."
 
   def RunStep(self):
     # Update v8 remote tracking branches.
     self.GitFetchOrigin()
     self.Git("fetch origin +refs/tags/*:refs/tags/*")
 
 
@@ skipping 120 matching lines @@
       DetermineV8Sheriff,
       SwitchChromium,
       UpdateChromiumCheckout,
       UploadCL,
       CleanUp,
     ]
 
 
 if __name__ == "__main__":  # pragma: no cover
   sys.exit(ChromiumRoll().Run())