Docs.rs build is broken for 50.1.0

[alamb]

Describe the bug

@wiedld reports that docs.rs build didn't work for the 50.1.0 release:

https://docs.rs/crate/datafusion/latest

To Reproduce

No response

Expected behavior

No response

Additional context

No response

[alamb]

Thankfully, @mbrobbel already fixed this in

• Fix docs.rs build: Replace auto_doc_cfg with doc_cfg #17845

[alamb]

We will backport the fix for 50.2.0 release

[alamb]

With the release of 50.2.0 the docs are now fixed

https://docs.rs/datafusion/latest/datafusion/index.html