Clarify comment per review

Author: willingc

source/conf.py

@@ -107,7 +107,8 @@
     # Temporarily ignored. Ref:
     # https://github.com/pypa/packaging.python.org/pull/1308#issuecomment-1775347690
     "https://www.breezy-vcs.org/*",
-    # Blocked due to https://github.com/pypa/packaging.python.org/pull/1474
+    # Ignore while StackOverflow is blocking GitHub CI. Ref:
+    # https://github.com/pypa/packaging.python.org/pull/1474
     "https://stackoverflow.com/*",
 ]
 linkcheck_retries = 5