Add Bookstack blueprint with Docker Compose and configuration files

- Introduced Docker Compose setup for Bookstack service, including environment variables and volume configuration.
- Added logo for Bookstack.
- Created template.toml for Bookstack with default variables for configuration.

blueprints/bookstack/docker-compose.yml

@@ -0,0 +1,35 @@
+version: "3.8"
+services:
+  bookstack:
+    image: lscr.io/linuxserver/bookstack:24.12.1
+    restart: unless-stopped
+    ports:
+      - 80
+    environment:
+      - PUID=1000
+      - PGID=1000
+      - APP_URL=http://${DOMAIN}
+      - DB_HOST=bookstack-db
+      - DB_USERNAME=mariadb
+      - DB_PASSWORD=${DB_PASSWORD}
+      - DB_DATABASE=bookstack
+      - APP_KEY=${APP_KEY}
+    volumes:
+      - config:/config
+    depends_on:
+      - bookstack-db
+
+  bookstack-db:
+    image: mariadb:10.11
+    restart: unless-stopped
+    environment:
+      - MYSQL_ROOT_PASSWORD=${DB_PASSWORD}
+      - MYSQL_DATABASE=bookstack
+      - MYSQL_USER=mariadb
+      - MYSQL_PASSWORD=${DB_PASSWORD}
+    volumes:
+      - db_data:/var/lib/mysql
+
+volumes:
+  config: {}
+  db_data: {}