Docs: fix typo in openstack builder
@ -317,7 +317,7 @@ VM.
``` json
{
"type": "openstack",
"identity_endpoint": "http://<destack-ip>:5000/v3",
"identity_endpoint": "http://<devstack-ip>:5000/v3",
"tenant_name": "admin",
"domain_name": "Default",
"username": "admin",