Update developer guide to highlight a couple of requirements #746

	name: Deploy web

	on:
	push:
	branches:
	- '**'
	- '!gh-pages'

	jobs:
	build:
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v3
	with:
	fetch-depth: 0

	- name: Install node
	uses: actions/setup-node@v3
	with:
	node-version: 18.x
	cache: 'npm'

	- name: Install wasm-pack
	uses: jetli/wasm-pack-action@v0.4.0

	- name: Cache WASM build
	uses: actions/cache@v3
	with:
	path: route_info/target
	key: doesnt-matter-share-everything

	- name: Build all branches
	run: \|
	mkdir deployme
	for branch in $(git branch -r \| grep -vE "origin/gh-pages" \| sed 's/origin\///'); do
	echo "Building $branch"
	git checkout $branch
	if [ "$branch" == "main" ]; then
	base=/atip/
	else
	base=/atip/$branch
	fi

	# TODO New build step not present in all branches yet. Rebase them all and remove.
	npm ci
	if npm run setup-govuk; then
	echo "GOV.UK setup successful"
	else
	echo "GOV.UK setup failed, continuing"
	fi

	if npm run wasm-release && npm ci && npm run generate-schema-ts && npm run build --if-present -- --base=$base; then
	if [ "$branch" == "main" ]; then
	mv dist/* deployme
	else
	mv dist deployme/$branch
	fi
	else
	echo "Building $branch broke; skipping"
	fi

	# TODO generate-schema-ts modifies some files that're still in
	# git on some old branches. Workaround by making that git diff
	# disappear, so changing branches later works.
	git checkout src/schemas
	done

	- name: Publish
	uses: peaceiris/actions-gh-pages@v3
	with:
	github_token: ${{ secrets.GITHUB_TOKEN }}
	publish_dir: ./deployme/

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