Add note about print-schema and table!

[konstin]

I do prefer table! over infer_schema! as I like both explicit code and builds that do not rely on a database. It was difficult to find table! and just chance I discovered diesel print-schema, so I added both to the guide.

[konstin]

The typos are fixed and everything is squashed in one commit. I've been much too sloppy with that pull request.

[killercup]

Thanks!