Fix ingress.yaml service/port, make custom domain more obvious

[matt-perrotti]

Just set this up today so two things would make this easier for others to understand:

1. Made MY_EXTERNAL_DOMAIN for unique subdomain in YAML files.
2. Noticed that service for ingress.yaml should be juice-balancer, not just balancer, and needed port 3000, not 8080.

Feel free to reject these edits if they aren't helpful but it took me a bit to figure some of this out so figured this might help others as well.

[J12934]

Hi @matt-perrotti,
sorry for the confusion. The problems with the port come from the upcoming 8.0.0 release, i changed the naming from juice-balancer to just balancer and the default balancer port to 8080. I already update the docs so that i don't forget about it, but i should have added a disclaimer somewhere to look at the 7.x branch for the time being. will add this to the readme.

The MY_EXTERNAL_DOMAIN we can definitly do, if that would have helped you 👍
Can you change the PR / open a new onew with just that change? Happy to merge that.

[matt-perrotti]

@J12934 I reverted the ingress.yaml change but left MY_EXTERNAL_DOMAIN in this PR.