#35 Add the command that solves the port issue in macOS.

README.md

@@ -122,6 +122,19 @@ podman run -v $PWD/Notebooks:/home/formation/gettingstartedwithmoderncpp:U -p 88
 
 See the [Docker](#option-2-docker) section for explanations about most of the options here; the main discrepancy is the `:U`added in the volume option.
 
+If you get an error message
+
+````
+Error: error preparing container XXXX for attach: something went wrong with the request: "listen tcp :8888: bind: address already in use\n"
+````
+
+make sure no container is already running and if not run (thanks to this [StackOverflow post](https://stackoverflow.com/questions/37971961/docker-error-bind-address-already-in-use)):
+
+````
+podman rm -f $(podman ps -aq)
+````
+
+
 For users of ARM chip: don't bother with the
  `WARNING: image platform ({amd64 linux  [] }) does not match the expected platform ({arm64 linux  [] })` 
  message; the notebooks work just fine in our case as far as I can tell.