docs: document resourcesPreset usage for kafka controller (#1493)

charts/sentry/values.yaml

@@ -2045,7 +2045,8 @@ kafka:
     enabled: true
   controller:
     replicaCount: 3
-
+    ## if the load on the kafka controller increases, resourcesPreset must be increased
+    # resourcesPreset: small # small, medium, large, xlarge, 2xlarge
   ## Use this to enable an extra service account
   # serviceAccount:
   #   create: false