r.drain: fix module keywords

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@71996 15284696-431f-4ddb-bdfa-cd5b030d7da7

scripts/r.drain/r.drain.py

@@ -21,7 +21,9 @@
 
 #%module
 #% description: Traces a flow through an elevation model or cost surface on a raster map.
-#% keyword: raster, hydrology, cost surface
+#% keyword: raster
+#% keyword: hydrology
+#% keyword: cost surface
 #%end
 #%option
 #% key: input