message: Remove out-dated comment about flow annotation
diff: @@ -156,7 +156,6 @@ ECMAScript
  - Be careful mixing arrow functions and regular functions, eg. if one function in a promise chain is an
  arrow function, they probably all should be.
  - Apart from that, newer ES features should be used whenever the author deems them to be appropriate.
  -- While flow annotations are welcome and encouraged consider to migrate the JS file to TypeScript (see next section).
  TypeScript
  ----------
  