k8s: migrate docs from docs/k8s

kubernetes/README.md

 # Kubernetes (k8s)
 
-## Running with Minikube
+## Minikube prerequisites
 
-See docs.
+```sh
+$ minikube start
+
+# Enable ingress addon
+$ minikube addons enable ingress
+
+# Continue below (Deploy step)
+```
 
 ## Deploy
 
 ```sh
+# Configure Kubernetes secrets
+# Replace HOST/USER/PSWD with secrets found in the 'secrets-docker' repository
+$ kubectl create secret docker-registry regcred --docker-server=HOST --docker-username=USER --docker-password=PSWD
+
 # Build Helm Charts
 $ helm dep build