* chore(docs): migrate & document all Page events
Rather than a generic `Events.ts` file we can instead document events as
an enum within each individual class. It's easier to document and work
with, and it's clearer where events originate from.
* chore(docs): reduce warnings when generating docs
This is a bunch of small miscellaneous fixes that reduce the amount of
warnings logged when generating our new docs. The long term goal is to
get this list down to 0 warnings, but I'll do it in multiple PRs.
* satisfy doclint
These files will be used by both the web and node versions of Puppeteer.
Another name for this might be "core" but I don't want to cause
confusion with the puppeteer-core package that we publish at the moment.
