message: doc: fix outdated docstring on Span constructor
diff: @@ -105,7 +105,8 @@ export class Span implements SpanInterface {
  public transaction?: Transaction;
  /**
  - * You should never call the constructor manually, always use `hub.startSpan()`.
  + * You should never call the constructor manually, always use `Sentry.startTransaction()`
  + * or call `startChild()` on an existing span.
  * @internal
  * @hideconstructor
  * @hidden
  