Improve _to_fake_sortable_semver() description

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

src/frequenz/repo/config/mkdocs/mike.py

@@ -143,14 +143,17 @@ def build_mike_version(repo_info: RepoVersionInfo) -> MikeVersionInfo:
 
 
 def _to_fake_sortable_semver(version: str) -> str:
-    """Convert a version string to a semver string.
+    """Convert a branch version string to a semver string.
 
     The following transformations are applied:
 
     - `vX.Y`     -> `X.Y.0`
     - `vX.Y-pre` -> `X.Y.99999`
     - `vX.Y-dev` -> `X.Y.999999`
 
+    The idea is to convert the version string to a semver string that can be sorted
+    together with proper semver tags using the semver built-in sorting.
+
     Args:
         version: The version string to convert.