message: docs: use `pipe` method for showing usage of operators as pure functions
diff: @@ -129,11 +129,11 @@ function mySimpleOperator(someCallback) {
  }
  ```
  -This can now be used with the `let()` method on the Observable:
  +This can now be used with the `pipe()` method on the Observable:
  <!-- skip-example -->
  ```js
  -const obs = someObservable.let(mySimpleOperator(x => x + '!'));
  +const obs = someObservable.pipe(mySimpleOperator(x => x + '!'));
  ```
  ## Publish your operator as a separate library
  