* New core-extensions to allow Docker volumes for third-party extensions
#Fix https://github.com/FreshRSS/FreshRSS/issues/2650
Split our extensions directory into two:
1) Core extensions shipped with FreshRSS in ./lib/core-extensions/
2) Third-party extensions modified by end-users in ./extensions/ which
can easily be mounted as a Docker volume
* Example of Docker Compose with extensions
* Back-compatibility + fix array merge bug
* 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.
* 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.
Mike Vanbuskirk