check-missing-*-in-docs job does not install Rust

[BD103]

In ci.yml, both check-missing-examples-in-docs and check-missing-features-in-docs do not install Rust before running it. This means that they are instead using the implicitly installed Rust tools that come with the ubuntu-latest image.

This is an issue because the image versions of Rust may not update in lockstep with the rest of the Bevy project. Our current MSRV policy is "latest stable." If the image installation is behind, it may cause the jobs to spuriously fail.

To fix this, dtolnay/rust-toolchain@stable should used. See other jobs such as build for reference.

bevy/.github/workflows/ci.yml

Lines 308 to 317 in 1df41b7

	check-missing-examples-in-docs:
	runs-on: ubuntu-latest
	timeout-minutes: 30
	steps:
	- uses: actions/checkout@v4
	- name: check for missing metadata
	id: missing-metadata
	run: cargo run -p build-templated-pages -- check-missing examples
	- name: check for missing update
	run: cargo run -p build-templated-pages -- update examples

bevy/.github/workflows/ci.yml

Lines 341 to 349 in 1df41b7

	check-missing-features-in-docs:
	runs-on: ubuntu-latest
	timeout-minutes: 30
	needs: check-missing-examples-in-docs
	steps:
	- uses: actions/checkout@v4
	- name: check for missing features
	id: missing-features
	run: cargo run -p build-templated-pages -- check-missing features

[BD103]

I'm going to wait for #13040 to be merged before working on this, so we can immediately use the new cache system.