Document how to source bink

Update README with the instructions how to source bink api expose

Signed-off-by: Alice Frosi <afrosi@redhat.com>

Author: alicefr

README.md

@@ -94,6 +94,8 @@ bink cluster start
 bink api expose
 export KUBECONFIG=$PWD/kubeconfig-podman
 kubectl get pods -A
+# Or directly from the shell
+eval $(bink api expose)
 
 # Add worker nodes (optional)
 bink node add node2