[kong] clarify HPA requirements (#236)

#### What this PR does / why we need it:
Adds values.yaml comments to clarify HPA requirements and `ingressController.resources` usage.

#### Special notes for your reviewer:
Thought it was possible to do this instead at the Pod level, since the controller doesn't consume a significant amount of resources and there's not much reason to handle it separately from the Kong container's requests, but it looks like that's a no go--docs sorta imply you can do it, but there's not actually any way to do that in the Pod spec.

#### Checklist
[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]
- [x] PR is based off the current tip of the `next` branch and targets `next`, not `main`
- [x] Title of the PR and commit headers start with chart name (e.g. `[kong]`)


* [kong] clarify HPA requirements

Update values.yaml comments to show an example controller resource limit
setting and indicate that you must set both when using an HPA.

* pr: apply suggestions

Co-authored-by: Michał Flendrich <[email protected]>

Co-authored-by: Michał Flendrich <[email protected]>

values.yaml

@@ -373,6 +373,14 @@ ingressController:
  successThreshold: 1
  failureThreshold: 3
  resources: {}
+ # Example reasonable setting for "resources":
+ # resources:
+ # limits:
+ # cpu: 100m
+ # memory: 256Mi
+ # requests:
+ # cpu: 50m
+ # memory: 128Mi
 
 # -----------------------------------------------------------------------------
 # Postgres sub-chart parameters
@@ -484,6 +492,8 @@ deploymentAnnotations:
  traffic.sidecar.istio.io/includeInboundPorts: ""
 
 # Enable autoscaling using HorizontalPodAutoscaler
+# When configuring an HPA, you must set resource requests on all containers via
+# "resources" and, if using the controller, "ingressController.resources" in values.yaml
 autoscaling:
  enabled: false
  minReplicas: 2