Switch from `domain.host` to new format

[meain]

What does this PR change?

Rename domain.host to domain.root in values.yaml. The actual name to be replaced is still to be finalized. Started this PR just to have a discussion around it.

Does the PR depend on any other PRs or Issues? If yes, please list them.

No

Checklist

I confirm, that I have...

• [x] Read and followed the contributing guide in CONTRIBUTING.md
• [ ] ~Added tests for this PR~
• [ ] ~Formatted the code using go fmt (if applicable)~
• [x] Updated documentation on the Paralus docs site (if applicable)
• [ ] ~Updated CHANGELOG.md~

[meain]

fqdn:
  # -- root domain
  domain: paralus.local
  # -- used for viewing dashboard
  hostname: “console”
  # -- a wildcard subdomain used for controller cluster to target
  # -- cluster communication
  coreConnectorSubdomain: “*.core-connector”
   # -- a wildcard subdomain used for controller cluster to end user
   # -- communication
   userSubdomain: “*.user”