clarify the doc

python/private/config_settings.bzl

@@ -36,15 +36,17 @@ def _flag_values(python_versions):
  python_versions: list of strings; all X.Y.Z python versions
 
  Returns:
- A map with config settings as keys and values as extra flag values to be included in
- the config_setting_group if they should be also matched, which is used for generating
- correct entries for matching the latest 3.8 version, etc.
+ A map with config settings as keys and values are all of the python_version flag
+ values that that match the given 'key' specification. For example:
+ ```
+ "3.8" -> ["3.8", "3.8.1", "3.8.2", ..., "3.8.19"] # All 3.8 versions
+ "3.8.2" -> ["3.8.2"] # Only 3.8.2
+ "3.8.19" -> ["3.8.19", "3.8"] # The latest version should also match 3.8 so
+ as when the `3.8` toolchain is used we just use the latest `3.8` toolchain.
+ this makes the `select("is_python_3.8.19")` work no matter how the user
+ specifies the latest python version to use.
+ ```
  """
-
- # Maps e.g.
- # "3.8" -> ["3.8", "3.8.1", "3.8.2", ..., "3.8.19"]
- # "3.8.2" -> ["3.8.2"] # no extra versions
- # "3.8.19" -> ["3.8.19", "3.8"] # The last version should also match 3.8
  ret = {}
 
  for micro_version in sorted(python_versions, key = _ver_key):