message: Clarify `ReactionsRow` forceUpdate usage
diff: @@ -68,6 +68,9 @@ export default class ReactionsRow extends React.PureComponent {
  this.setState({
  myReactions: this.getMyReactions(),
  });
  + // Using `forceUpdate` for the moment, since we know the overall set of reactions
  + // has changed (this is triggered by events for that purpose only) and
  + // `PureComponent`s shallow state / props compare would otherwise filter this out.
  this.forceUpdate();
  }
  