docs: restructure documentation

This rewrite follows the principles of https://diataxis.fr/

Co-authored-by: Erik Michelson <github@erik.michelson.eu>
Signed-off-by: Philip Molares <philip.molares@udo.edu>
Signed-off-by: Erik Michelson <github@erik.michelson.eu>

.github/workflows/docs-netlify-deploy.yml

@@ -0,0 +1,55 @@
+# SPDX-FileCopyrightText: 2023 The HedgeDoc developers (see AUTHORS file)
+#
+# SPDX-License-Identifier: AGPL-3.0-only
+
+name: Deploy HD2 docs to Netlify
+
+on:
+  push:
+    branches: [ develop ]
+    paths: ['docs/**']
+
+env:
+  NETLIFY_VERSION: 13.2.2
+  NODEJS_VERSION: 20
+  PYTHON_VERSION: 3.11
+
+defaults:
+  run:
+    working-directory: docs
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}-${{ github.job }}
+  cancel-in-progress: true
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    name: Deploys to netlify
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # v3.5.3
+
+      - name: Setup node
+        uses: ./.github/actions/setup-node
+        with:
+          NODEJS_VERSION: ${{ env.NODEJS_VERSION }}
+
+      - name: Set up Python
+        uses: actions/setup-python@v1
+        with:
+          python-version: ${{ env.PYTHON_VERSION }}
+
+      - name: Install dependencies
+        run: pip install -r requirements.txt
+
+      - name: Build docs
+        run: mkdocs build
+
+      - name: Install netlify CLI
+        run: "yarn add --dev netlify-cli@${{ env.NETLIFY_VERSION }}"
+
+      - name: Run netlify CLI deployment
+        env:
+          NETLIFY_AUTH_TOKEN: ${{ secrets.NETLIFY_AUTH_TOKEN }}
+        run: "netlify deploy --build --prod --message \"${{ github.event.head_commit.id }}\""