Update comments for net/data/verify_certificate_chain_unittest/

net/data/verify_certificate_chain_unittest/target-has-keycertsign-but-not-ca/generate-chains.py

Index: net/data/verify_certificate_chain_unittest/target-has-keycertsign-but-not-ca/generate-chains.py
diff --git a/net/data/verify_certificate_chain_unittest/target-has-keycertsign-but-not-ca/generate-chains.py b/net/data/verify_certificate_chain_unittest/target-has-keycertsign-but-not-ca/generate-chains.py
index 01f4509d2466d9177135e5bc27112d81c2c7c45b..8be0639d9fa793918aa455fef79718155b10e2dc 100755
--- a/net/data/verify_certificate_chain_unittest/target-has-keycertsign-but-not-ca/generate-chains.py
+++ b/net/data/verify_certificate_chain_unittest/target-has-keycertsign-but-not-ca/generate-chains.py
@@ -3,17 +3,16 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-"""Certificate chain with 1 intermediate, a trusted root, and a target
-certificate that is not a CA, and yet has the keyCertSign bit set. Verification
-is expected to fail, since keyCertSign should only be asserted when CA is
-true."""
+"""Certificate chain where the leaf certificate asserts the keyCertSign key
+usage, however does not have CA=true in the basic constraints extension to
+indicate it is a CA."""
 
 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.