Enable nightly to have scraping examples for dev-docs generation

[ShadowMitia]

Objective

• Show scraped examples in docs.rs

Solution

• cargo doc needs the nightly channel. Local experiments showed that explicitly setting the unstable rustdoc-scrape-examples flag seems to work better than setting in the Cargo.toml.

[mockersf]

This is not for docs.rs, this is for https://dev-docs.bevyengine.org/bevy/index.html

docs.rs issue is related to rust-lang/docs.rs#2305

[ShadowMitia]

This is a tentative solution, I'm not familiar enough with github workflows...

I have seen some of the issues on the subject, and the PR merged (for 0.11.1 I believe), everything looks fine.
I think the issue is mainly to make sure the nightly channel needs to be set.
I am unsure why setting the flags works better, they might not be necessary.

Hope I'm not stepping on anyone's toes here. If I am feel free to close this PR.
I'm explicitly allowing reuse without attribution just in case.

[ShadowMitia]

@mockersf Ah I didn't go deep enough it seems... Sorry about that...
This was already tested and didn't work...

Closing this PR.

[mockersf]

In my opinion it's still interesting to enable scraping examples on the dev-docs, so this PR makes sense!

[ShadowMitia]

Enabling nightly should be enough then, and whatever needs to be done as well for docs.rs.
So waiting on rust-lang/docs.rs#2305 to be closed?

[ShadowMitia]

#2305 was merged, so this is now mergeable!

[BD103]

This line needs to be changed to @nightly, or the CI will fail. See docs on action.

bevy/.github/workflows/docs.yml

Lines 36 to 37 in b6e154f

	- name: Install Rust
	uses: dtolnay/rust-toolchain@stable

Edit: This may also let you remove the +nightly modifier, since it will be the only toolchain installed.

[ShadowMitia]

@BD103 All done! Thanks!

[mockersf]

done in #12223, sorry I forgot about this PR