Add versionadded info

Doc/api/init.tex

@@ -276,6 +276,7 @@
   Return a string representing the Subversion revision that this Python
   executable was built from.  This number is a string because it may contain a
   trailing 'M' if Python was built from a mixed revision source tree.
+  \versionadded{2.5}
 \end{cfuncdesc}
 
 \begin{cfuncdesc}{const char*}{Py_GetPlatform}{}

Doc/lib/libsys.tex

@@ -31,6 +31,7 @@ It is always available.
   A string representing the Subversion revision that this Python executable
   was built from.  This number is a string because it may contain a trailing
   'M' if Python was built from a mixed revision source tree.
+  \versionadded{2.5}
 \end{datadesc}  
 
 \begin{datadesc}{builtin_module_names}