This release adds webhooks to our description!

In the 3.0.1 (./descriptions) version the webhooks are located at the top-level
`x-webhooks` extension.

In the 3.1.0 version (./descriptions-next), which supports webhooks as an attribute
on the [OpenApi
Object](https://spec.openapis.org/oas/v3.1.0.html#openapi-object), they
are located under `webhooks`.

Merge pull request github#1594 from github/openapi-update-0624009df56…

…ca0a5d51196d7d204438063db29d76374b8def1a5c5534f1a1f2a

Update OpenAPI 3.1 Descriptions

GA Release of OpenAPI 3.0 description.