Rename compose file the official preferred way

See https://docs.docker.com/compose/intro/compose-application-model/#the-compose-file

.github/CONTRIBUTING.md

@@ -20,7 +20,7 @@ You'll then have:
 
 You can now access your wallabag instance using that url: `http://127.0.0.1:8000`
 
-If you want to test using an other database than SQLite, uncomment the `postgres` or `mariadb` code from the `docker-compose.yml` file at the root of the repo. Also uncomment related line in the `php` section so the database will be linked to your PHP instance.
+If you want to test using an other database than SQLite, uncomment the `postgres` or `mariadb` code from the `compose.yaml` file at the root of the repo. Also uncomment related line in the `php` section so the database will be linked to your PHP instance.
 
 ### Using your own PHP server
 

.gitignore

@@ -15,7 +15,7 @@
 .php-cs-fixer.cache
 .phpunit.result.cache
 phpunit.xml
-docker-compose.override.yml
+compose.override.yaml
 
 # Parameters
 /app/config/parameters.yml