message: docs(README): remove beta references.
diff: @@ -44,7 +44,7 @@ By contributing or commenting on issues in this repository, whether you've read
  ### ES6 via npm
  ```sh
  -npm install rxjs@beta
  +npm install rxjs
  ```
  To import only what you need by patching (this is useful for size-sensitive bundling):
  @@ -65,7 +65,7 @@ Alternatively, you can use the built-in `pipe` method on Observables. See [pipea
  To install this library for CommonJS (CJS) usage, use the following command:
  ```sh
  -npm install rxjs@beta
  +npm install rxjs
  ```
  (Note: destructuring available in Node 8+)
  