chore: remove old docs app (#4749)

.github/workflows/build-docs.yml

@@ -1,32 +0,0 @@
-name: Build Docs
-on:
-  workflow_call:
-
-permissions:
-  contents: read
-  
-jobs:
-  build:
-    name: Build Docs
-    runs-on: ubuntu-latest
-    timeout-minutes: 30
-
-    steps:
-      - uses: actions/checkout@v3
-      - uses: ./.github/actions/dangerous-git-checkout
-
-      - name: Setup Node.js 20.x
-        uses: actions/setup-node@v3
-        with:
-          node-version: 20.x
-
-      - name: Install pnpm
-        uses: pnpm/action-setup@v4
-
-      - name: Install dependencies
-        run: pnpm install --config.platform=linux --config.architecture=x64
-        shell: bash
-
-      - run: |
-          pnpm build --filter=@formbricks/docs...
-        shell: bash