Add spec identifier syntax to input-format.md #1996

	name: CI
	on:
	pull_request:
	merge_group:

	env:
	MDBOOK_VERSION: 0.4.40
	# When updating, be sure to also update rust-lang/rust.
	MDBOOK_SPEC_VERSION: 0.1.0

	jobs:
	test:
	name: Test
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@master
	- name: Cache
	uses: actions/cache@v4
	with:
	path: \|
	~/.cargo/bin/
	~/.cargo/.crates.toml
	~/.cargo/.crates2.json
	key: ms-${MDBOOK_SPEC_VERSION}
	- name: Update rustup
	run: rustup self update
	- name: Install Rust
	run: \|
	rustup set profile minimal
	rustup toolchain install nightly -c rust-docs,rustfmt
	rustup default nightly
	- name: Install mdbook
	run: \|
	mkdir bin
	curl -sSL https://github.com/rust-lang/mdBook/releases/download/v${MDBOOK_VERSION}/mdbook-v${MDBOOK_VERSION}-x86_64-unknown-linux-gnu.tar.gz \| tar -xz --directory=bin
	echo "$(pwd)/bin" >> $GITHUB_PATH
	- name: Report versions
	run: \|
	rustup --version
	rustc -Vv
	mdbook --version
	- name: Install mdbook-spec
	run: cargo install --locked mdbook-spec@${MDBOOK_SPEC_VERSION}
	- name: Run tests
	run: mdbook test
	- name: Style checks
	working-directory: style-check
	run: cargo run -- ../src
	- name: Style fmt
	working-directory: style-check
	run: cargo fmt --check
	- name: Check for broken links
	run: \|
	curl -sSLo linkcheck.sh \
	https://raw.githubusercontent.com/rust-lang/rust/master/src/tools/linkchecker/linkcheck.sh
	sh linkcheck.sh --all reference

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