Backport of Add docs for k8s liveness / startup probes. into release/1.16.x (#20226)

* backport of commit 31796a7

* backport of commit febc574

---------

Co-authored-by: Derek Menteer <derek.menteer@hashicorp.com>
Co-authored-by: Derek Menteer <105233703+hashi-derek@users.noreply.github.com>

Author: hc-github-team-consul-core

website/content/docs/k8s/annotations-and-labels.mdx

@@ -251,6 +251,9 @@ The following Kubernetes resource annotations could be used on a pod to control
 - `consul.hashicorp.com/sidecar-proxy-lifecycle-graceful-port` - Override the default Helm value [`connectInject.sidecarProxy.lifecycle.defaultGracefulPort`](/consul/docs/k8s/helm#v-connectinject-sidecarproxy-lifecycle-defaultgracefulport)
 - `consul.hashicorp.com/sidecar-proxy-lifecycle-graceful-shutdown-path` - Override the default Helm value [`connectInject.sidecarProxy.lifecycle.defaultGracefulShutdownPath`](/consul/docs/k8s/helm#v-connectinject-sidecarproxy-lifecycle-defaultgracefulshutdownpath)
 
+- `consul.hashicorp.com/sidecar-proxy-startup-failure-seconds` - Override the default Helm value [`connectInject.sidecarProxy.defaultStartupFailureSeconds`](/consul/docs/k8s/helm#v-connectinject-sidecarproxy-defaultstartupfailureseconds)
+- `consul.hashicorp.com/sidecar-proxy-liveness-failure-seconds` - Override the default Helm value [`connectInject.sidecarProxy.defaultLivenessFailureSeconds`](/consul/docs/k8s/helm#v-connectinject-sidecarproxy-defaultlivenessfailureseconds)
+
 - `consul.hashicorp.com/enable-metrics` - Override the default Helm value [`connectInject.metrics.defaultEnabled`](/consul/docs/k8s/helm#v-connectinject-metrics-defaultenabled).
 - `consul.hashicorp.com/enable-metrics-merging` - Override the default Helm value [`connectInject.metrics.defaultEnableMerging`](/consul/docs/k8s/helm#v-connectinject-metrics-defaultenablemerging).
 - `consul.hashicorp.com/merged-metrics-port` - Override the default Helm value [`connectInject.metrics.defaultMergedMetricsPort`](/consul/docs/k8s/helm#v-connectinject-metrics-defaultmergedmetricsport).

website/content/docs/k8s/helm.mdx

@@ -2173,6 +2173,9 @@ Use these links to navigate to a particular top-level stanza.
 
       - `defaultGracefulShutdownPath` ((#v-connectinject-sidecarproxy-lifecycle-defaultgracefulshutdownpath)) (`string: /graceful_shutdown`)
 
+    - `defaultStartupFailureSeconds` ((#v-connectinject-sidecarproxy-defaultstartupfailureseconds)) (`integer: 0`) - Enables a startup probe that polls the Envoy sidecar health every second. When a container fails health checks consecutively for this period of time during startup, K8s restarts the container according to its [`restartPolicy`](https://kubernetes.io/docs/concepts/workloads/pods/pod-lifecycle/#restart-policy). A value of `0` disables the probe.
+    - `defaultLivenessFailureSeconds` ((#v-connectinject-sidecarproxy-defaultlivenessfailureseconds)) (`integer: 0`) - Enables a liveness probe that polls the Envoy sidecar health every second. When a container fails health checks  for this period of time, K8s restarts the container according to its [`restartPolicy`](https://kubernetes.io/docs/concepts/workloads/pods/pod-lifecycle/#restart-policy). A value of `0` disables the probe.
+
   - `initContainer` ((#v-connectinject-initcontainer)) (`map`) - The resource settings for the Connect injected init container. If null, the resources
     won't be set for the initContainer. The defaults are optimized for developer instances of
     Kubernetes, however they should be tweaked with the recommended defaults as shown below to speed up service registration times.