nixos/ollama: make host example dualstack wildcard

Binding to IPv6 wildcard generally binds dual-stack, which is also a
better example because the way to specify it is not always very clear.

nixos/modules/services/misc/ollama.nix

@@ -70,7 +70,7 @@ in
       host = lib.mkOption {
         type = types.str;
         default = "127.0.0.1";
-        example = "0.0.0.0";
+        example = "[::]";
         description = ''
           The host address which the ollama server HTTP interface listens to.
         '';