added references to Debian package reposiroty

client/README.txt

@@ -38,7 +38,21 @@ Install from package
    - https://git.autistici.org/p/djrandom/dist/DJRandomUploader.zip
 
    Linux (Debian/Ubuntu):
-   - https://git.autistici.org/p/djrandom/dist/djrandom-client_0.2.3_all.deb
+   - Add the following repository to your list of APT sources (you
+     can simply create /etc/apt/sources.list.d/djrandom.list for
+     that if your apt is recent enough):
+
+       deb http://git.autistici.org/p/djrandom/debian unstable main
+
+     Install the repository GPG key with:
+
+       $ wget -O- http://git.autistici.org/p/djrandom/debian/repo.key \
+         | sudo apt-key add -
+
+     Then update and install the djrandom-client package:
+
+       $ sudo apt-get update
+       $ sudo apt-get install djrandom-client
 
 
 Running the client