pythonlib: note region_env() in dox documentation

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@51060 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/python/pythonlib.dox

@@ -156,6 +156,8 @@ Returns the name of a temporary file, created with g.tempfile.
 
  - python::core::region()
 
+ - python::core::region_env()
+
  - python::core::use_temp_region()
 
 <b>Interface to g.findfile</b>