Description of problem:

Currently, our document states that we should set 4GB swap on all compute nodes:
Note: Controller node doesn't have this sentence.

https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/17.1/html-single/installing_and_managing_red_hat_openstack_platform_with_director/index#ref_compute-node-requirements_planning-your-overcloud
Configure at least 4 GB of swap space.

However, Director doesn't configure swap on overcloud nodes by default.

<from my RHOSP 17.1 lab>
[root@central-novacompute-0 ~]# swapon
[root@central-novacompute-0 ~]# free -h
               total        used        free      shared  buff/cache   available
Mem:            24Gi       1.3Gi        23Gi        12Mi       573Mi        23Gi
Swap:             0B          0B          0B

Do we really need swap for overcloud nodes?
If swap is needed, I suppose Director should configure swap by default, or at least our document should have some instructions to configure swap.

Version-Release number of selected component (if applicable):
RHOSP 17.1

How reproducible:
Steps to Reproduce:
1. Deploy RHOSP 17.1 normaly

Actual results:
Swap is not configured on overcloud nodes.

Expected results:
Swap is configured on overcloud nodes.
(Or should we remove "Configure at least 4 GB of swap space" sentence from our documentation?)