Revamp speech configuration documentation; add examples

[vmarshall]

This was for a take home. I would be very wary of my additions :-)

[sahilsuman933]

Hey @vmarshall, the doc update is looking fantastic - nice work! A couple of tweaks could take it up a notch:

1. The Accordion group at the start is solid, but it doesn’t quite click as a fit for the speech configuration topic. Maybe we zero in on how it ties to turn-taking or reframe it a bit?
2. It’d be awesome to add details about the custom endpointing feature. You’ll find the info in our Swagger API reference: https://api.vapi.ai/api.

These small adjustments could really sharpen the flow and clarity. Let me know if you need a hand!

[vmarshall]

Removed the conversation accordian to it's own page: https://github.com/vmarshall/vapi_docs/blob/update-speech-config/fern/customization/conversational-analysis.mdx?plain=1

If that's ok, I can do a different pull request

[vmarshall]

Added docs for transport plans
https://github.com/vmarshall/vapi_docs/blob/update-speech-config/fern/customization/speech-configuration.mdx