Fix up a couple things in API field docs.
Review Request #14260 — Created Dec. 4, 2024 and updated — Latest diff uploaded
The docs for fields across our API resources leave a lot to be desired,
but I came across some truly egregious things while working on the
RBTools stuff. This change fixes up a completely incorrect MIME type in
the WebHook resource, and some terrible grammar in the root comment
resources.
Ran unit tests.