Update README.md #446

	# This is a basic workflow to help you get started with Actions

	name: Test build

	# Controls when the action will run.
	on:
	# Triggers the workflow on push or pull request events but only for the main branch
	push:
	branches: [ main ]
	pull_request:
	branches: [ main ]

	# Allows you to run this workflow manually from the Actions tab
	workflow_dispatch:

	# A workflow run is made up of one or more jobs that can run sequentially or in parallel
	jobs:
	# This workflow contains a single job called "build"
	build:
	# The type of runner that the job will run on
	runs-on: ubuntu-latest

	# Steps represent a sequence of tasks that will be executed as part of the job
	steps:

	- name: Try to restore opam cache
	id: opam-cache
	uses: actions/cache@v2
	with:
	path: "~/.opam"
	key: opam-${{github.base_ref}}-${{github.ref}}
	restore-keys: \|
	opam--refs/heads/${{github.base_ref}}

	- name: Install OCaml
	uses: avsm/setup-ocaml@v1
	with:
	ocaml-version: 4.09.1

	# Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
	- name: Checkout repo
	uses: actions/checkout@v2

	# Runs a set of commands using the runners shell
	- name: Build
	run: \|
	opam repo add coq-released https://coq.inria.fr/opam/released
	opam install coq.8.16.0 coq-equations.1.3+8.16 coq-mathcomp-ssreflect.1.15.0 coq-mathcomp-analysis.0.5.3 coq-extructures.0.3.1 coq-deriving.0.1.0
	opam exec -- make -j4

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