Update on Promises
Update on Promises

It seems that with ES6 Promises being apparently used, the reference to `done()` is outdated.

Also clarifies that it is "problematic" to discard the results of promises rather than it being an "error" .
matrix-org/matrix-js-sdk,matrix-org/matrix-js-sdk,matrix-org/matrix-js-sdk,matrix-org/matrix-js-sdk