Field documentation

[nbigaouette-eai]

It'd be interesting to be able to add (structs' and fields') fields documentation.

For example:

let mut scope = Scope::new();

scope.new_struct("Foo").field("bar", "i64", "This is a `bar`");

could generate:

struct Foo {
 /// This is a `bar`
 bar: i64,
}

Or maybe a Field type would be useful which could be push_field()ed to a Struct, similarly to Scope::push_struct()?

[carllerche]

👍 I would probably not include the doc string as a third argument as that could get unwieldy.

A push_field would most definitely be useful either way, so we can add doc (and annotation) support to that.