docs: introduce batch requests

[wolovim]

What was wrong?

batch_requests api needs documenting

Todo:

• Clean up commit history
• Add or update documentation related to these changes
• Add entry to the release notes

Cute Animal Picture

[fselmo]

Looks great. Left some nits but really I'm even thinking too hard about them I think... take or leave.

[fselmo]

Oh, it will be important to capture the async functionality as well since the await is not required when adding requests to the batch. However, when executing, it will need to be awaited via await batch.async_execute().