docs: Link to compatibility matrix for imageEnvoy (#7387)

* docs: Link to compatibility matrix for imageEnvoy

Added a link to the Envoy supported version in the documentation for `imageEnvoy` parameter.

* Update website/source/docs/platform/k8s/helm.html.md

website/source/docs/platform/k8s/helm.html.md

@@ -467,7 +467,7 @@ to run the sync program.
 
   * <a name="v-connectinject-imageConsul" href="#v-connectinject-imageConsul">`imageConsul`</a> (`string: global.image`) - The name of the Docker image (including any tag) for Consul. This is used for proxy service registration, Envoy configuration, etc.
 
-  * <a name="v-connectinject-imageEnvoy" href="#v-connectinject-imageEnvoy">`imageEnvoy`</a> (`string: ""`) - The name of the Docker image (including any tag) for the Envoy sidecar. `envoy` must be on the executable path within this image. This Envoy version must be compatible with the Consul version used by the injector. This defaults to letting the injector choose the Envoy image, which is usually `envoyproxy/envoy-alpine`.
+  * <a name="v-connectinject-imageEnvoy" href="#v-connectinject-imageEnvoy">`imageEnvoy`</a> (`string: ""`) - The name of the Docker image (including any tag) for the Envoy sidecar. `envoy` must be on the executable path within this image. This Envoy version must be compatible with the Consul version used by the injector. If not specified this defaults to letting the injector choose the Envoy image. Check [supported Envoy versions](/docs/connect/proxies/envoy.html#supported-versions) to ensure the version you are using is compatible with Consul.
 
   * <a name="v-connectinject-namespaceselector" href="#v-connectinject-namespaceselector">`namespaceSelector`</a> (`string: ""`) - A [selector](https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/) for restricting injection to only matching namespaces. By default all namespaces except `kube-system` and `kube-public` will have injection enabled.