Macros not visible in documentation

[bluss]

Rustdoc doesn't show macros in module documentation or in search anymore

• See std::macros

[alexcrichton]

I believe this is a consequence of #15601 because macros are no longer in the AST. We could just lift all macros into their own top-level "module" in the crate now because that's essentially where they are anyway.

cc @jbclements, but I don't think that we should revert that change.

[jbclements]

Yes, I agree. The spans are all in a single vector at the top level of the crate. Let me know if I can help with this.

[alexcrichton]

Closing, this was fixed in #15751.