clarify changelog

Author: rickeylev

CHANGELOG.md

@@ -55,11 +55,13 @@ END_UNRELEASED_TEMPLATE
 {#v0-0-0-changed}
 ### Changed
 
-* If using the autodetecting/runtime_env toolchain, then the Python version
-  specified at build-time *must* match the Python version used at runtime (the
-  {obj}`--@rules_python//python/config_settings:python_version` flag controls the
-  build-time version). (Such a misconfiguration was unlikely to work to begin
-  with; this is called out as an FYI).
+* If using the (deprecated) autodetecting/runtime_env toolchain, then the Python
+  version specified at build-time *must* match the Python version used at
+  runtime (the {obj}`--@rules_python//python/config_settings:python_version`
+  flag and the {attr}`python_version` attribute control the build-time version
+  for a target). If they don't match, dependencies won't be importable. (Such a
+  misconfiguration was unlikely to work to begin with; this is called out as an
+  FYI).
 * (rules) {obj}`--bootstrap_impl=script` is the default for non-Windows.
 * (rules) On Windows, {obj}`--bootstrap_impl=system_python` is forced. This
   allows setting `--bootstrap_impl=script` in bazelrc for mixed-platform