debian/README.source updated

In Jessie, pbuilder disables the network by default, and we need it
to build our packages. Also currently only Jessie debs are built successfully,
and building for wheezy fails because of missing video libraries.

debian/README.source

@@ -67,10 +67,12 @@ If you want actualy Debian binary or source packages to upload to your
 own repository, you'll need to build them as described here.  We have
 some fancy automatic tools to accomplish this.  The tools allow you to
 start from a very bare Debian image and generate working packages.
-Building in this manner is only supported on Debian sid, though it
-will generate packages for all supported Debian releases.  Simply run:
+Building in this manner is only supported on Debian jessie, though it
+will generate packages for all supported Debian releases. Simply run as root:
 
-    ./debian/util.sh build-all -ibn -z9
+    echo "USENETWORK=yes" >$HOME/.pbuilderrc
+
+    ./debian/util.sh build-all -ibn -z9 -aamd64 -cjessie
 
 Building on Ubuntu
 ------------------