Fix build on nightly

[rajivshah3]

The build fails on the nightly toolchain because of the following error:

error[E0557]: feature has been removed
 --> ~/.cargo/registry/src/github.51.al-1ecc6299db9ec823/pharos-0.5.1/src/lib.rs:1:33
  |
1 | #![ cfg_attr( nightly, feature( external_doc, doc_cfg    ) ) ]
  |                                 ^^^^^^^^^^^^ feature has been removed
  |
  = note: use #[doc = include_str!("filename")] instead, which handles macro invocations

error: aborting due to previous error

For more information about this error, try `rustc --explain E0557`.
error: could not compile `pharos`

I think this PR should resolve the issue

[najamelan]

Hi, yes. I'm in the process of updating my libs. However, this will require an extra cfg_attr, otherwise it will still try to evaluate include_str! on stable... So it should be:

#![cfg_attr( nightly, cfg_attr( nightly, doc = include_str!("../README.md") ) )]

See: rust-lang/rust#82768

[rajivshah3]

Ooh, ok 👍

[najamelan]

Do you want to push force the fix? Then I will merge it in and release a new version.

[najamelan]

Version 0.5.2 has been released.