Expanded documentation on how to run (orphan containers)

docs/how_to_run.md

@@ -102,7 +102,9 @@ RABOTNIK_VERBOSITY=3
 ## Steps
 
 1. If not already running, start the `rabotnik` container by doing
-`docker-compose up -d rabotnik` from the directory where `docker-compose.yml` is located.
+`docker-compose up -d --remove-orphans rabotnik` from the directory where `docker-compose.yml`
+is located. The `--remove-orphans` flag is relevant to avoid older versions of the container to
+keep on running in the background.
 2. Create a .txt file with a list of OpenStreetMap (OSM) IDs of buildings to process and name
 it as per your preference. E.g. `my_buildings.txt` (see example below).
 3. Place `my_buildings.txt` in a directory of your choice.
@@ -119,6 +121,10 @@ list of OSM IDs to be processed. As a consequence, whenever passing on a new lis
 `rabotnik` container does not need to be stopped and re-started, only the `rcom` container needs
 such actions.
 
+Note: If prompted by a warning from Docker (of the kind "Found orphan containers for this
+project"), use the `--remove-orphans` flag when starting the containers (either `rcom` or
+`rabotnik`).
+
 Example of the format for `my_buildings.txt`:
 
 ```