[doc] Fix a few margins due to bad markup (GH-23619)



diff --git a/Doc/library/platform.rst b/Doc/library/platform.rst
index fc51b5d..be86e56 100644
--- a/Doc/library/platform.rst
+++ b/Doc/library/platform.rst
@@ -290,4 +290,4 @@
               ids.extend(info["ID_LIKE"].split())
           return ids
 
-  .. versionadded:: 3.10
+   .. versionadded:: 3.10