Update comments for net/data/verify_certificate_chain_unittest/

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

Index: net/data/verify_certificate_chain_unittest/target-has-pathlen-but-not-ca/generate-chains.py
diff --git a/net/data/verify_certificate_chain_unittest/target-has-pathlen-but-not-ca/generate-chains.py b/net/data/verify_certificate_chain_unittest/target-has-pathlen-but-not-ca/generate-chains.py
index 44405c93a3c752849f56358fc9c759d995366644..ee7692295db92ce9a89d1c4ce90091b1cf02275b 100755
--- a/net/data/verify_certificate_chain_unittest/target-has-pathlen-but-not-ca/generate-chains.py
+++ b/net/data/verify_certificate_chain_unittest/target-has-pathlen-but-not-ca/generate-chains.py
@@ -3,16 +3,15 @@
 # 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 a pathlen set. Verification is
-expected to fail, since pathlen should only be set for CAs."""
+"""Certificate chain where the leaf has a basic constraints extension with
+CA=false, however specifies the optional pathlen."""
 
 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.