explicitly allow running command to manually generating tokens from forgejo machine

additionally serves to document the needed command, for future
automation.

machines/dev/vm02116/forgejo.nix

@@ -110,4 +110,8 @@ in
       };
     };
   };
+
+  # needed to imperatively run forgejo commands e.g. to generate runner tokens.
+  # example: `sudo su - forgejo -c 'nix-shell -p forgejo --run "gitea actions generate-runner-token -C /var/lib/forgejo/custom"'`
+  users.users.forgejo.isNormalUser = true;
 }