[docs] Mention our channels (#11336)

* Mention our communication channels

* Apply suggestions from Shu

Co-Authored-By: Shu Uesugi <shu@chibicode.com>

* Update getting-started.md

Co-authored-by: Shu Uesugi <shu@chibicode.com>
Co-authored-by: Tim Neutkens <tim@timneutkens.nl>

docs/getting-started.md

@@ -10,6 +10,8 @@ If you're new to Next.js we recommend that you start with the [learn course](htt
 
 The interactive course with quizzes will guide you through everything you need to know to use Next.js.
 
+If you have questions about anything related to Next.js, you're always welcome to ask our community on [GitHub Discussions](https://github.com/zeit/next.js/discussions).
+
 #### System Requirements
 
 - [Node.js 10](https://nodejs.org/) or later