Add more information to the Gather REST API request demos & Docs

[dtolb]

In order to combine an audio request to the Gather, please use the prompt value of the gather request

This would look something like:

prompt = voice_api.build_sentence(sentence = "Hello from Bandwidth, please press some digits")
gather_id = voice_api.create_call_gather(call_id, prompt = prompt);

Where the voice_api.build_sentence let's you construct the prompt. If you're using audio playback, there is a similar method build_audio_playback that would be used for the prompt instead.

See the transfer docs for how an example could look.

It could also be worth adding the prompt value directly in the param list instead of relying on **kwargs, no real opinion here.

Todo

• Add example to the Gather documentation for sentence
• Add example to the Gather documentation for playAudio