docx: very work in progress k8s creds doc

Author: Kevin Bimonte

docs/docs/operation/creds/kubernetes.md

@@ -2,6 +2,25 @@
 title: Kubernetes Credential Manager
 ---
 
+Concourse can be configured to pull credentials
+from [Kubernetes `secret` objects](https://kubernetes.io/docs/concepts/configuration/secret).
+
+To configure it, either enable the in-cluster client by setting the following environment variable on
+the [`web` node](../../install/running-web.md):
+
+```properties
+CONCOURSE_KUBERNETES_IN_CLUSTER=true
+```
+
+or set the path to a `kubeconfig` file:
+
+```properties
+CONCOURSE_KUBERNETES_CONFIG_PATH=~/.kube/config
+```
+
 ## Credential lookup rules
 
+When resolving a parameter such as `((foo))`, Concourse will look for it in the following order in the namespace
+configured for that team:
+
 ## Configuring Kubernetes RBAC