docs: Small update to install docs (#14477)

Author: JStickler

docs/sources/setup/install/helm/install-microservices/_index.md

@@ -26,7 +26,7 @@ It is not recommended to run scalable mode with `filesystem` storage. For the pu
 **Prerequisites**
 
 - Helm 3 or above. See [Installing Helm](https://helm.sh/docs/intro/install/).
-- A running Kubernetes cluster.
+- A running Kubernetes cluster (must have at least 3 nodes).
 - (Optional) A Memcached deployment for better query performance. For information on configuring Memcached, refer to the [caching section](https://grafana.com/docs/loki/<LOKI_VERSION>/operations/caching/).
 
 

docs/sources/setup/install/helm/install-scalable/_index.md

@@ -28,7 +28,7 @@ It is not recommended to run scalable mode with `filesystem` storage. For the pu
 **Prerequisites**
 
 - Helm 3 or above. See [Installing Helm](https://helm.sh/docs/intro/install/).
-- A running Kubernetes cluster.
+- A running Kubernetes cluster (must have at least 3 nodes).
 - (Optional) A Memcached deployment for better query performance. For information on configuring Memcached, refer to [caching section]({{< relref "../../../../operations/caching" >}}).