README: note Docker/Boulder network requirements
Boulder needs to access port 5002. If a firewall's in the way, tests
fail with cryptic timeout errors.
@@ -31,6 +31,8 @@ docker-compose run -e FAKE_DNS=192.168.1.65 --service-ports boulder ./start.py
```
where ```192.168.1.65``` is the address my Apache httpd is listening on.
+When running the tests, make sure your Docker instance is able to access port
+5002 on the host.
## Changes
