ensure double blank line before a subsection

Author: picnixz

Doc/whatsnew/3.15.rst

@@ -295,6 +295,7 @@ dbm
   This may harm performance, but improve crash tolerance.
   (Contributed by Serhiy Storchaka in :gh:`66234`.)
 
+
 difflib
 -------
 
@@ -379,6 +380,7 @@ os.path
   the resulting path can be missing but it will be free of symlinks.
   (Contributed by Petr Viktorin for :cve:`2025-4517`.)
 
+
 resource
 --------
 
@@ -726,6 +728,7 @@ Deprecated C APIs
   :c:func:`_Py_c_abs` are :term:`soft deprecated`.
   (Contributed by Sergey B Kirpichev in :gh:`128813`.)
 
+
 .. Add C API deprecations above alphabetically, not here at the end.
 
 Removed C APIs