feat: added Adminer usage description in the README

README.md

@@ -59,6 +59,16 @@ Then in the root directory run `docker-compose up -d` to build, (re)create, star
 
 When you are finished, run `docker-compose down` to stop and remove containers, networks and images created by `up`.
 
+### Adminer
+With Adminer we can manage our PostgreSQL database.
+
+To login to Adminer in your browser you need to specify:
+* System: `PostgreSQL`
+* Server: `postgres` (docker-compose database service name)
+* Username: same as `DB_USER` in your .env file
+* Password: same as `DB_PASSWORD` in your .env file
+* Database: same as `DB_NAME` in your .env file
+
 ## TODO
 
 More TBA as features are implemented.