Merge branch 'minor-improvement-to-k8s-monitoring-docs' into 'master'

Improve link for CI environment variable, wording.

See merge request gitlab-org/gitlab-ce!17252

doc/user/project/integrations/prometheus_library/kubernetes.md

@@ -28,6 +28,6 @@ Prometheus server up and running. You have two options here:
 
 In order to isolate and only display relevant CPU and Memory metrics for a given environment, GitLab needs a method to detect which containers it is running. Because these metrics are tracked at the container level, traditional Kubernetes labels are not available.
 
-Instead, the [Deployment](https://kubernetes.io/docs/concepts/workloads/controllers/deployment/) or [DaemonSet](https://kubernetes.io/docs/concepts/workloads/controllers/daemonset/) name should begin with the name of the [environment](../../../../ci/environments.md). It can be followed by a `-` and additional content if desired. For example, a deployment name of `review-homepage-5620p5` would match the `review/homepage` environment.
+Instead, the [Deployment](https://kubernetes.io/docs/concepts/workloads/controllers/deployment/) or [DaemonSet](https://kubernetes.io/docs/concepts/workloads/controllers/daemonset/) name should begin with [CI_ENVIRONMENT_SLUG](../../../../ci/variables/README.md#predefined-variables-environment-variables). It can be followed by a `-` and additional content if desired. For example, a deployment name of `review-homepage-5620p5` would match the `review/homepage` environment.
 
-If you are using [GitLab Auto-Deploy](../../../../ci/autodeploy/index.md) and one of the two [provided Kubernetes monitoring solutions](../prometheus.md#getting-started-with-prometheus-monitoring), the naming will be correctly set automatically.
+If you are using [GitLab Auto-Deploy](../../../../ci/autodeploy/index.md) and one of the two [provided Kubernetes monitoring solutions](../prometheus.md#getting-started-with-prometheus-monitoring), the `environment` label will be automatically added.