Add more info to README

README.md

@@ -16,14 +16,18 @@ services:
             DOWNLOAD_POLY: https://download.geofabrik.de/europe/germany/berlin.poly
         volumes:
             - ./osm-data:/data/database
-        cmd: run
+        command: run
 ```
 
-Specify a PBF file for the region that you want to render and its corresponding polygon as `DOWNLOAD_PBF` and `DOWNLOAD_POLY`. Alternatively, mount one [converted to O5M](https://wiki.openstreetmap.org/wiki/Osmconvert) as `/data/region.o5m` and `/data/region.poly`. Get a specific region from [Geofabrik](https://download.geofabrik.de/) or the whole planet from [Planet.osm](https://wiki.openstreetmap.org/wiki/Planet.osm) (in that case, `DOWNLOAD_POLY` can be omitted).
+Specify a PBF file for the region that you want to render and its corresponding polygon as `DOWNLOAD_PBF` and `DOWNLOAD_POLY`. Get a specific region from [Geofabrik](https://download.geofabrik.de/) or the whole planet from [Planet.osm](https://wiki.openstreetmap.org/wiki/Planet.osm) (in that case, `DOWNLOAD_POLY` can be omitted).
 
-The docker container will expose a webserver under port `80` and the Postgres server (with PostGIS) on port `5432`.
+Alternatively, mount an O5M file as `/data/region.o5m` and a `/data/region.poly`. To convert a PBF file to O5M, you can use something like `wget -O- https://download.geofabrik.de/europe/germany/berlin-latest.osm.pbf | docker run -i --rm --entrypoint= facilmap/openptmap osmconvert - --out-o5m > berlin-latest.o5m`.
 
 Before starting the container for the first time, initialize the database by running:
 ```bash
 docker-compose run --rm openptmap import
-```
+```
+
+This will initialize a Postgres database with PostGIS and import the region into it. The PBF/Poly files are only used during the import, they are not needed anymore later when the service is run. If you want to import the region again, you need to empty the volume and run the import again.
+
+The docker container will expose a webserver under port `80` and the Postgres server (with PostGIS) on port `5432`.