Correct docker-compose.yml file and add a corresponding note in the doc. (#1906)

* Add a docker compose example.

Using postgresql and with traefik specific labels.

* Added docker-compose specific documentation.

* Move docker-compose section at the end of the README.md.

* Correct docker-compose.yml file and add a corresponding note in the doc.

* Typo in doc.

Docker/README.md

@@ -160,11 +160,12 @@ with HTTPS, for instance using [Let’s Encrypt](https://letsencrypt.org/).
 
 A [docker-compose.yml](docker-compose.yml) file is given as an example, using PostgreSQL. In order to use it, you have to adapt:
 - In the `postgresql` service:
-	* the `volumes` section;
+	* the `volumes` section. Be careful to keep the path `/var/lib/postgresql/data` for the container. If the path is wrong, you will not get any error but your db will be gone at the next run;
 	* the `POSTGRES_PASSWORD` in the `environment` section;
 - In the `freshrss` service:
 	* the `volumes` section;
 	* options under the `labels` section are specific to [Træfik](https://traefik.io/), a reverse proxy. If you are not using it, feel free to delete this section. If you are using it, adapt accordingly to your config, especially the `traefik.frontend.rule` option.
+	* the `environment` section to adapt the strategy to update feeds.
 
 You can then launch the stack (postgres + freshrss) with:
 ```sh

Docker/docker-compose.yml

@@ -5,7 +5,7 @@ services:
     image: postgres:latest
     restart: unless-stopped
     volumes:
-    - '/path/to/pgsql-data:/var/lib/postgresql/data:Z'
+    - '/path/to/pgsql-data:/var/lib/postgresql/data'
     environment:
     - POSTGRES_USER=freshrss
     - POSTGRES_PASSWORD=password
@@ -20,7 +20,7 @@ services:
       - web
       - default
     volumes:
-      - '/your/local/directory/data:/var/www/FreshRSS/data:Z'
+      - '/your/local/directory/data:/var/www/FreshRSS/data'
     labels:
       - "traefik.backend=freshrss"
       - "traefik.docker.network=web"
@@ -29,6 +29,8 @@ services:
       - "traefik.default.protocol=http"
       - "traefik.frontend.entryPoints=http,https"
       - "traefik.port=80"
+    environment:
+      - CRON_MIN=*/20
 
 networks:
   web: