website: deploy website from GitHub Actions (#3237)

Deploying GitHub Pages from the gh-pages branch is a classic way.
We can use actions/deploy-pages action to deploy GitHub Pages.

scripts/update-website

@@ -1,30 +0,0 @@
-#!/bin/bash
-
-# This script builds the website from the docs directory of
-# the current branch and copies it over to the gh-pages
-# branch.
-
-set -eux
-shopt -s dotglob
-
-# build website
-scriptdir=$(dirname "$0")
-cd "$scriptdir"/../docs
-rm -rf output
-mkdir output
-pipenv run python3 build_website.py
-cd ..
-
-# copy to /tmp
-tmpdir=$(mktemp -d -t jq.website.XXXXXXXXXX)
-cp -r docs/output/* "$tmpdir"
-cp .gitignore "$tmpdir"
-
-# copy to gh-pages
-git checkout gh-pages
-cp -r "$tmpdir"/* .
-cp "$tmpdir"/.gitignore .
-
-# clean up
-rm -rf "$tmpdir"
-echo SUCCESS