update CONTRIBUTING.md to include MacOS resolver configuration instructions

Author: pomdtr

CONTRIBUTING.md

@@ -12,4 +12,10 @@ You can follow the instructions from the [docs](https://www.smallweb.run/docs/ho
 
 > [!WARNING] Make sure to trust the certificate generated by caddy by running the `caddy trust` command.
 
+If you're using MacOS, you'll also need to create the `/etc/resolver/localhost` file with the following content:
+
+```sh
+nameserver 127.0.0.1
+```
+
 Then, all debug commands will use the example workspace located in the `examples` folder.