Polish documentation

Signed-off-by: Benoit Donneaux <benoit@leastauthority.com>

morph/grid/local/README.rst

@@ -62,7 +62,7 @@ Use the local development environment
     morph push grid.nix
     morph deploy grid.nix boot
     vagrant halt
-    vagrant up --no-destroy-on-error # Add `--no-parallel` on low resources
+    vagrant up
     morph upload-secrets grid.nix
 
 You should now be able to log in with the users and keys you set in your ``users.nix`` file.