[runtimeconfig] Should be "client.config(...)" not "client.get_config(...)

[DazWilkin]

https://github.com/GoogleCloudPlatform/google-cloud-python/blob/bee32c0ae68b1e6cf224f9017c758a8e31e8be83/runtimeconfig/google/cloud/runtimeconfig/config.py#L189

[tseaver]

Thanks, the client class does indeed have a config method (rather than get_config).

In addition, that example has a typo, get_varialbe.