Create `CONTRIBUTING.md` #609

	name: CI

	on:
	pull_request:
	push:
	branches:
	- staging
	- trying

	jobs:
	check:
	name: check
	runs-on: ubuntu-latest
	strategy:
	matrix:
	build: [msrv, stable]
	features:
	[
	"",
	"--no-default-features",
	"--no-default-features --features use_alloc",
	"--all-targets --all-features",
	]
	include:
	- build: msrv
	rust: 1.62.1
	- build: stable
	rust: stable
	exclude:
	- build: msrv
	# we only care about the MSRV with respect to the lib target
	features: "--all-targets --all-features"
	steps:
	- uses: actions/checkout@v4
	- uses: dtolnay/rust-toolchain@master
	with:
	toolchain: ${{ matrix.rust }}
	- run: cargo check ${{ matrix.features }}

	test:
	name: test
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v4
	- uses: dtolnay/rust-toolchain@stable
	- run: cargo test --all-features

	check-format:
	name: check format
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v4
	- uses: dtolnay/rust-toolchain@master
	with:
	toolchain: stable
	components: rustfmt
	- run: cargo fmt --check

	# https://github.com/rust-lang/crater/blob/9ab6f9697c901c4a44025cf0a39b73ad5b37d198/.github/workflows/bors.yml#L125-L149
	end-success:
	name: bors build finished
	if: success()
	runs-on: ubuntu-latest
	needs: [check, test]

	steps:
	- name: Mark the job as successful
	run: exit 0

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