docs: fix auth validation text and platform-specific verify commands

Correct grammar in authentication validation rule messages and split service
verification commands so Kubernetes and OpenShift/OKD use supported resource types.

Author: mangelajo

python/docs/source/getting-started/configuration/authentication.md

@@ -111,7 +111,7 @@ $ kubectl -n dex create secret tls dex-tls \
     --key=pki/private/dex.dex.svc.cluster.local.key
 ```
 
-2. Install Dex using your preferred deployment method with the following equivalent configuration:
+2. Install Dex with Helm using the following `values.yaml`:
 
 ```yaml
 https:
@@ -165,9 +165,15 @@ $ kubectl create clusterrolebinding oidc-reviewer  \
     --group=system:unauthenticated
 ```
 
-Then deploy Dex in the `dex` namespace with this configuration applied.
+Then install Dex:
 
-3. Configure Jumpstarter to trust Dex by setting `spec.authentication.jwt`:
+```console
+$ helm repo add dex https://charts.dexidp.io
+$ helm install --namespace dex --wait -f values.yaml dex dex/dex
+```
+
+3. Configure Jumpstarter to trust Dex. Use this configuration for
+   `jumpstarter-controller.authenticationConfiguration` during installation:
 
 ```yaml
 spec:
@@ -289,7 +295,7 @@ spec:
       # validation rules applied to the final user object.
       userValidationRules:
       - expression: "!user.username.startsWith('system:')"
-        message: 'username cannot used reserved system: prefix'
+        message: 'username cannot use reserved system: prefix'
       - expression: "user.groups.all(group, !group.startsWith('system:'))"
-        message: 'groups cannot used reserved system: prefix'
+        message: 'groups cannot use reserved system: prefix'
 ```

python/docs/source/getting-started/installation/service/service-operator.md

@@ -192,7 +192,8 @@ Check CR status and workloads:
 
 ```{code-block} console
 $ kubectl get jumpstarter -n jumpstarter-lab
-$ kubectl get deploy,svc,ingress,route -n jumpstarter-lab
+$ kubectl get deploy,svc,ingress -n jumpstarter-lab   # Kubernetes
+$ kubectl get deploy,svc,route -n jumpstarter-lab     # OpenShift/OKD
 ```
 
 ```{note}

python/docs/source/getting-started/installation/service/service-production.md

@@ -46,11 +46,11 @@ Choose one of these TLS termination approaches:
 gRPC over HTTP/1.1 is not supported. Ensure your ingress controller supports HTTP/2 and is properly configured for gRPC traffic.
 ```
 
-## Install with Operator
+## Installation
 
-If you prefer operator-managed installation and reconciliation, see [Install with Operator](service-operator.md). That guide includes:
+To install Jumpstarter, see [Install with Operator](service-operator.md). That guide includes:
 
-- Installing the operator from the release asset (`operator-installer.yaml`)
+- Installing the operator from the release asset (`operator-installer.yaml`), OperatorHub and OLM.
 - Creating a `Jumpstarter` custom resource for vanilla Kubernetes with Ingress
 - Creating a `Jumpstarter` custom resource for OpenShift with Routes
 - Notes on integrating external OAuth/OIDC and cert-manager setups