Ensure Dockerfile is compatible with Smithery

[JoshMock]

Smithery server setup is currently failing. The docs say:

We only support Linux Docker images on major distros (Alpine/Debian-based) and expect sh to run in your container. Other distros are untested and may not deploy.

We're using a Wolfi image, which should theoretically work, but may need to have sh manually installed on it to work with Smithery.

[swallez]

Do we really want to support (and promote) Smithery? Why this one and not others? The PR adding Smithery integration was contributed by Smithery's founder.

I'd be in favor of removing all references to Smithery.

[JoshMock]

Removed smithery.yml in #155.