Add ssh hosts to the ssh configuration file

shared/home-manager.nix

@@ -167,7 +167,19 @@ in
     };
   };
 
-  ssh.enable = true;
+  ssh = {
+    enable = true;
+    matchBlocks = {
+      optimisation = {
+        hostname = "compute.optimisation-2020.cloud.edu.au";
+        user = "dekker1";
+      };
+      nitrogen = {
+        hostname = "nitrogen.dekker.li";
+        user = "jdekker";
+      };
+    };
+  };
 
   starship = {
     enable = true;