Add system requirements for macos/windows

ref: kubernetes-sigs#156

/kind documentation

Signed-off-by: Jorge Alarcon Ochoa <alarcj137@gmail.com>

docs/user/README.md

@@ -18,6 +18,14 @@ By default, the cluster will be given the name `kind-1`. "1," here, is the
 default context name. 
 Use the `--name` flag to assign the cluster a different context name.
 
+**Note**: If you are running `kind` of MacOS or Windows then it is recommended
+you have at least 4GB of RAM and disk space dedicated to the virtual machine 
+(vm) running the Docker engine otherwise the Kubernetes cluster might fail to 
+start up.
+If you come across erros where `kubectl` cannot communicate with the cluster
+and you have increased the memory and size of the VM, then try cleaning up
+space by performing a `docker system prune`.
+
 
 ## Interacting With Your Cluster
 After [creating a cluster](#creating-a-cluster), you can use [kubectl][kubectl]
@@ -87,7 +95,7 @@ The `node-image` in turn is built off the [`base-image`][base image], which
 installs all the dependencies needed for Docker and Kubernetes to run in a
 container.
 
-See [base image](#base-image), for more advanced information information.
+See [base image](#base-image), for more advanced information.
 
 Currently, `kind` supports three different ways to build a `node-image`: via
 `apt`, or if you have the [Kubernetes][kubernetes] source in your host machine