helm: standardize yaml configuration (#15728)

- move application variables under `mastodon` namespace
- restore standard yaml structure for ingress configuration
- move values.yaml.template to values.yaml

chart/readme.md

@@ -3,12 +3,9 @@
 This is a [Helm](https://helm.sh/) chart for installing Mastodon into a
 Kubernetes cluster.  The basic usage is:
 
-```
-cp values.yaml.template values.yaml
-edit values.yaml # configure required settings
-helm dep update
-helm upgrade --install my-mastodon ./
-```
+1. edit `values.yaml` or create a separate yaml file for custom values
+1. `helm dep update`
+1. `helm install --namespace mastodon --create-namespace my-mastodon ./ -f path/to/additional/values.yaml`
 
 This chart has been tested on Helm 3.0.1 and above.
 
@@ -16,14 +13,11 @@ This chart has been tested on Helm 3.0.1 and above.
 
 The variables that _must_ be configured are:
 
-- `ingress.hostname`; even if you aren’t using an Ingress, this value is used to
-  set `LOCAL_DOMAIN`.
-
-- password and keys in the `secrets`, `postgresql`, and `redis` groups; if
+- password and keys in the `mastodon.secrets`, `postgresql`, and `redis` groups; if
   left blank, some of those values will be autogenerated, but will not persist
   across upgrades.
 
-- SMTP settings for your mailer in the `smtp` group.
+- SMTP settings for your mailer in the `mastodon.smtp` group.
 
 # Missing features