Remove documentation in README, redirect to tezos-k8s.xyz (#469)

* Remove documentation in README, redirect to tezos-k8s.xyz

I have done a quick review, everything from the README was in the doc
except the section about indexers and the one about using a custom tezos
image. I have added them.

tezos-k8s.xyz is officially in MVP status, therefore it is good to send
people to it now, and improve it as we go.

* indexer: do not point to specific lines per review

* fix typo

* temp test deploy

* helm repo instructions in dedicated section in prereq

* Revert "temp test deploy"

This reverts commit 7ad9135.

* fix deployment problem - it keeps removing the special domain config