#![feature]` may not be used on the stable release channel

[lcmgh]

When trying to generate docs with cargo doc for my app I am facing this error after adding opentelemetry crates:

 Documenting opentelemetry-proto v0.1.0
error[E0554]: `#![feature]` may not be used on the stable release channel
 --> /Users/x/.cargo/registry/src/github.com-1ecc6299db9ec823/opentelemetry-proto-0.1.0/src/lib.rs:1:18
  |
1 | #![cfg_attr(doc, feature(doc_auto_cfg))]

[flokli]

It looks like this is due to the usage of doc_auto_cfg.

open-telemetry/opentelemetry-rust#924 might be the correct place for it (where the rust code seems to live in), it says it should not be an issue without the docsrs feature.

[tigrannajaryan]

Closing since open-telemetry/opentelemetry-rust#924 is resolved.