a.core_concepts.md minor issue

[leifliddy]

For the question Create the pod that was just described using YAML
When you create the pod.yaml file with
kubectl run nginx --image=nginx --restart=Never --dry-run=client -n mynamespace -o yaml > pod.yaml

The resulting yaml file will have the namespace listed in it ie

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: nginx
  name: nginx
  namespace: mynamespace
....

So, there's no need to specify the namespace when creating the pod with
kubectl create -f pod.yaml