* Completion API: add 'store' param
This param allows you to opt a completion request in to being stored,
for use in distillations and evals.
* Add cached and audio tokens to usage structs
These have been added to the completions API recently:
https://platform.openai.com/docs/api-reference/chat/object#chat/object-usage
* Add speech to text example in docs
* Add caption formats for audio transcription
* Add caption example to README
* Address sanity check errors
* Add tests for decodeResponse
* Use typechecker for audio response format
* Decoding response refactors
* Migrated examples to example_test.go
* Add some executable examples
* Update error docs
* Avoid linting example files which break conventions
* Restore README examples
* Enable linting for example_test
