hydra changes, readme fix.

README.md

 # argopkgs
 
 Nix-based CI with Hydra for Argo packages. Hydra is a versatile build farm. 
-For the moment, our instance is http://129.114.111.116:8080.
+
+## usage
+
+The instance is http://129.114.111.116:8080.
+A list of packages available so far is at:
+http://129.114.111.116:8080/jobset/argo/master#tabs-jobs
+
+### Using the argo binary cache on a system that has the nix package manager:
+```
+nix-channel --add http://129.114.111.116:8080/project/argo/channel/latest argo
+nix-channel --update
+```
+
+#### Installing all packaged argo software from the binary cache:
+```
+nix-env -iA argo
+```
+
+#### Installing a specific packaged argo software from the binary cache:
+```
+nix-env -iA argo.<packagename>
+```

deployments/ci.nix

@@ -45,7 +45,7 @@ in
         source = keys/id_buildfarm;
         uid = config.users.users.hydra-queue-runner.uid;
         gid = config.users.groups.hydra.gid;
-        mode = "0660";
+        mode = "0600";
       };
 
       nix = {
@@ -71,7 +71,7 @@ in
         hydraURL = "http://129.114.111.116";
         notificationSender = "hydra@example.org";
         port = 8080;
-        extraConfig = "binary_cache_secret_key_file = /etc/nix/hydra.example.org-1/secret";
+        extraConfig = "secret-key=/etc/nix/hydra.example.org-1/secret";
         buildMachinesFiles = [ "/etc/nix/machines" ];
       };