Adds readme file describing debian source package.

resources/install/README.Debian

@@ -0,0 +1,7 @@
+To create debian source package you need some other projects sources that
+jitsi depends on. In the same folder where jitsi is checked out do:
+git clone https://github.com/jitsi/otr4j.git
+git clone https://github.com/jitsi/libsrc.git
+And then in jitsi do: ant deb-src -Dlabel=4444
+This will create orig.tar.gz debian sources that can be used to debuild
+debian package.