mention debuild package build method (merge from devbr6)

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@34014 15284696-431f-4ddb-bdfa-cd5b030d7da7

debian/README.debian

@@ -8,6 +8,8 @@ svn co svn://svn.debian.org/pkg-grass/packages/grass/branches/6.3/debian .
 # After that, you can build current version of GRASS with
 
 dpkg-buildpackage -rfakeroot
+  or
+debuild binary
 
 # in main GRASS source directory. After the packages are generated, you can
 # install them with