chore: reduce redis-cluster pods and move HA out of "experimental" state (#565)

The pod reduction for `redis-cluster` should help users seeking for a Gitea deployment with less pods. Users seeking for a minimal deployment are further advised to follow https://gitea.com/gitea/helm-chart#user-content-single-pod-configurations.

HA is working fine in the provided configuration and should be moved out of the "experimental" state given that there were no reports of Gitea malfunctioning reported to HA usage in recent months/since v9 release.

Reviewed-on: https://gitea.com/gitea/helm-chart/pulls/565
Reviewed-by: techknowlogick <techknowlogick@noreply.gitea.com>
Co-authored-by: pat-s <patrick.schratz@gmail.com>
Co-committed-by: pat-s <patrick.schratz@gmail.com>

docs/ha-setup.md

@@ -1,7 +1,5 @@
 # High Availability
 
-⚠️ **EXPERIMENTAL** ⚠️
-
 All components (in-memory DB, volume/asset storage, code indexer) used by Gitea must be deployed in a HA-ready fashion to achieve a full HA-ready Gitea deployment.
 The following document explains how to achieve this for all individual components.
 
@@ -97,6 +95,11 @@ To do so, you need to set the following configuration values yourself:
 - `gitea.config.cache.ADAPTER`: `redis`
 - `gitea.config.cache.HOST`: `<your redis connection string>`
 
+By default, the `redis-cluster` chart provisions three standalone master nodes of which each has a single replica.
+To reduce the number of pods for a default Gitea deployment, we opted to omit the replicas (`replicas: 0`) by default.
+Only the minimum required number of master pods for a functional `redis-cluster` deployment are provisioned.
+For a "proper" `redis-cluster` setup however, we recommend to set `replicas: 1` and `nodes: 6`.
+
 ## Object and asset storage
 
 Object/asset storage refers to the storage of attachments, avatars, LFS files, etc.