Fixed ignore typo in web-go example.
Fixed ignore typo in web-go example.

We forgot to adjust the root ignore used in .mutagen.yml in c8b8b5e.

Signed-off-by: Jacob Howard <f862f167b85d41b225785c70d70808bc7337c1fe@havoc.io>

havoc-io/mutagen,havoc-io/mutagen