In this case, your custom domain will look like
https://docs.yourbusiness.com
.Log in to your Microsoft 365 admin center.
Click on Settings > Domains.
Choose your domain.
Go to the DNS records tab.
Click on the + Add record button.
Select CNAME (Alias) as the Type.
Fill in the Host name or Alias, Points to address, and TTL fields as seen on the custom domain setting page on NeetoKB.
Click on the Save button.