Add Public Docker Image and Build Pipeline using Github Actions (#546)

* feat: github action to build and push to dockerhub on release

* feat: docker repo and quickstart readmne

* fix: check for NEXTAUTH_SECRET in dockerfile before running

* fix: check for NEXTAUTH_SECRET as null or not

* add deployment guide

---------

Co-authored-by: Matthias Nannt <mail@matthiasnannt.com>

.github/workflows/release-on-dockerhub.yml

@@ -0,0 +1,40 @@
+name: Release Formbricks Image on Dockerhub
+
+on:
+  push:
+    tags:
+      - "v*"
+
+jobs:
+  release-image-on-dockerhub:
+    name: Release
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Repo
+        uses: actions/checkout@v2
+
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v2
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+
+      - name: Get Release Tag
+        id: extract_release_tag
+        run: |
+          TAG=${{ github.ref }}
+          TAG=${TAG#refs/tags/v}
+          echo "RELEASE_TAG=$TAG" >> $GITHUB_ENV
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v4
+        with:
+          context: .
+          file: ./apps/web/Dockerfile
+          push: true
+          tags: |
+            ${{ secrets.DOCKER_USERNAME }}/formbricks:${{ env.RELEASE_TAG }}
+            ${{ secrets.DOCKER_USERNAME }}/formbricks:latest