Incomplete edition descriptions

[linusg]

• The summary of ES2018 doesn't mention Promise.prototype.finally (b1a633f)
• The summary of ES2019 doesn't mention Symbol.prototype.description (4a2d6d0)

[michaelficarra]

Is this actionable? We don't really file errata, and even if we did, the non-normative yearly summary wouldn't be worth mentioning. I think the most I can do for you is an "oops" on behalf of the previous editor groups.

[linusg]

I now realize this is ambiguous - I'm not asking to amend the historical snapshots, I only care about the draft at https://tc39.es/ecma262/ which contains sections that start with:

ECMAScript 2019 introduced...

and

ECMAScript 2018 introduced...

[linusg]

For additional context: https://test262.fyi maps test262 features to ES editions. I've been validating what we have against those short summaries for test262-fyi/data@006e3e9 and noticed those two features are not mentioned.