Update opverpass api docs and env vars

Author: Rub21

images/overpass-api/README.md

@@ -1,3 +1,18 @@
 # Overpass api
 
-This continaer is base on: https://github.com/wiktorn/Overpass-API
+This continaer is base on: https://github.com/wiktorn/Overpass-API
+
+### Configuration
+
+In order to run this container we need environment variables, these can be found in the following files👇:
+
+- [..env.overpass.example](./../../envs/.env.overpass.example)
+
+**Note**: Rename the above files as `.env.overpass`
+
+#### Running nominatim - DB and API container
+
+```sh
+    # Docker compose
+    docker-compose run overpass-api
+```