pygrass manual: add missing import (PIPE)

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@65089 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/python/docs/src/pygrass_modules.rst

@@ -195,6 +195,7 @@ attributes of the class: ::
 
 Another example of use: ::
 
+    >>> from subprocess import PIPE
     >>> info = Module("r.info", map="elevation", flags="r", stdout_=PIPE)
     >>> from grass.script.utils import parse_key_val
     >>> parse_key_val(info.outputs.stdout)