Update comments for net/data/verify_certificate_chain_unittest/

net/data/verify_certificate_chain_unittest/target-wrong-signature/generate-chains.py

 #!/usr/bin/python
 # Copyright (c) 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-"""Certificate chain where the target has an incorrect signature. Everything
-else should check out, however the digital signature contained in the target
-certificate is wrong."""
+"""Certificate chain where the target certificate has an incorrect signature."""
 
 import sys
 sys.path += ['..']
 
 import common
 
-# Self-signed root certificate (used as trust anchor).
+# Self-signed root certificate.
 root = common.create_self_signed_root_certificate('Root')
 
 # Intermediate certificate to include in the certificate chain.
 intermediate = common.create_intermediate_certificate('Intermediate', root)
 
 # Actual intermediate that was used to sign the target certificate. It has the
 # same subject as expected, but a different RSA key from the certificate
 # included in the actual chain.
 wrong_intermediate = common.create_intermediate_certificate('Intermediate',
                                                             root)
 
 # Target certificate, signed using |wrong_intermediate| NOT |intermediate|.
 target = common.create_end_entity_certificate('Target', wrong_intermediate)
 
 chain = [target, intermediate, root]
 common.write_chain(__doc__, chain, 'chain.pem')