Add main netlify deployment on GH actions

Signed-off-by: Erik Michelson <github@erik.michelson.eu>

netlify/deploy-main.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+
+# SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+#
+# SPDX-License-Identifier: AGPL-3.0-only
+
+json=$(yarn netlify deploy --build --prod --json --message "${1:0:8}: $2")
+
+echo "${json}"
+
+url=$(echo "${json}" | jq -r .deploy_url)
+logs=$(echo "${json}" | jq -r .logs)
+
+echo "::set-output name=url::${url}"
+echo "::set-output name=logs::${logs}"