website(api-gateway): add consul namespace to helm install (#12644)

* website: api-gateway helm install consul namespace

To mirror instructions at https://learn.hashicorp.com/tutorials/consul/kubernetes-api-gateway

* website(api-gateway): add notes on where to find available versions

* website(api-gateway): fixup link to more clearly indicate Consul Helm chart releases

* Update website/content/docs/api-gateway/api-gateway-usage.mdx

website/content/docs/api-gateway/api-gateway-usage.mdx

@@ -25,7 +25,7 @@ Refer to [Technical Specifications](/docs/api-gateway/tech-specs) for minimum so
 
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-1. Create a `values.yaml` file for your Consul API Gateway deployment. Copy the content below into the `values.yaml` file. The `values.yaml` will be used by the Consul Helm chart. See [Helm Chart Configuration - apiGateway](https://www.consul.io/docs/k8s/helm#apigateway) for more available options on how to configure your Consul API Gateway deployment via the Helm chart.
+1. Create a `values.yaml` file for your Consul API Gateway deployment. Copy the content below into the `values.yaml` file. The `values.yaml` will be used by the Consul Helm chart. Available versions of the [Consul](https://hub.docker.com/r/hashicorp/consul/tags) and [Consul API Gateway](https://hub.docker.com/r/hashicorp/consul-api-gateway/tags) Docker images can be found on DockerHub, with additional context on version compatibility published in [GitHub releases](https://github.com/hashicorp/consul-api-gateway/releases). See [Helm Chart Configuration - apiGateway](https://www.consul.io/docs/k8s/helm#apigateway) for more available options on how to configure your Consul API Gateway deployment via the Helm chart.
 
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@@ -44,12 +44,12 @@ Refer to [Technical Specifications](/docs/api-gateway/tech-specs) for minimum so
 
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-1. Install Consul API Gateway using the standard Consul Helm chart and specify the custom values file.
+1. Install Consul API Gateway using the standard Consul Helm chart and specify the custom values file. Available versions of the [Consul Helm chart](https://github.com/hashicorp/consul-k8s/releases) can be found in GitHub releases.
 
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    ```shell-session
-   $ helm install consul hashicorp/consul --version 0.41.1 --values values.yaml
+   $ helm install consul hashicorp/consul --version 0.41.1 --values values.yaml --create-namespace --namespace consul
    ```
 
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