README: running published container image

Now that we have persistent user files, users can simply run the
published container image. We default to host networking so we will be
able to guess the WAS URL.

README.md

@@ -11,7 +11,13 @@ You will need to (one-time) configure, build, and flash Willow from the ```featu
 ./utils.sh flash-dist
 ```
 
-### WAS Installation
+### Running WAS
+
+```
+docker run --rm -it --env=OTA_URL="http://my_was_host:8502/static/ota.bin" --network=host ghcr.io/toverainc/willow-application-server:main
+```
+
+### Building WAS
 ```
 git clone https://github.com/toverainc/willow-application-server.git && cd willow-application-server