CP-3286 Selective mocking with fallback example needs to specify `fallThrough: true`

[evanweible-wf]

https://github.com/Workiva/w_transport/blob/master/docs/guides/MockSelectiveMockingWithFallback.md

[rmconsole2-wf]

It looks like you have not included any tickets in the title of this issue. Please create a ticket for this issue, or click here to have Rosie create one for you.