fixed typo

Signed-off-by: Matthew Stobbs <matthew@sprouting.cloud>

demilich/home.nix

@@ -18,7 +18,7 @@
     };
   };
   home = {
-    usrname = "${username}";
+    username = "${username}";
     homeDirectory = "/home/${username}";
     preferXdgDirectories = true;
     stateVersion = stateVersion;