Error in ruby documentation for associating authenticated domains with a subuser

[reedperkins]

I noticed an error in the ruby example for associating an authenticated domain with a subuser.

Currently, line 10 reads:

response = sg.client.whitelabel.domains._(domain_id).subuser:add.post(request_body: data)

The colon in subuser:add is invalid Ruby syntax. Really it should be:

response = sg.client.whitelabel.domains._(domain_id)._("subuser:add").post(request_body: data)

I opened a ticket with support and suggested the correction, and they said to create an issue here. I would be willing to create a PR for the fix, but I can't find where this example comes from in the repo.