tap Helm values reference

Helm values reference table for the tap application.

Key	Type	Default	Description
cadc-tap.config.backend	string	"qserv"	What type of backend?
cadc-tap.config.vaultSecretName	string	"tap"	Vault secret name: the final key in the vault path
cadc-tap.ingress.path	string	"tap"
cadc-tap.serviceAccount.name	string	"tap"
global.baseUrl	string	Set by Argo CD	Base URL for the environment
global.host	string	Set by Argo CD	Host name for ingress
global.vaultSecretsPath	string	Set by Argo CD	Base path for Vault secrets