Updated Install Wekan Docker in production (markdown)

Install-Wekan-Docker-in-production.md

@@ -19,6 +19,8 @@ wekan:
   environment:
     - MONGO_URL=mongodb://wekandb/wekan
     - ROOT_URL=http://localhost:8081
+  ports:
+    - 8081:80
 
 wekandb:
    image: mongo
@@ -26,6 +28,8 @@ wekandb:
      - /home/wekan/data:/data/db
 ```
 
+**Note:** we want to preserve the 80 port on the host, so we bind Wekan on port 8081, that next will be bound to a vhost in apache (thus on port 80)
+
 ## 3. Configure Apache as a front-end proxy
 
 * Enable Mod_Proxy: `sudo a2enmod proxy proxy_http` then restart Apache `service apache2 restart`