docs: add Discord as an official communication channel (angular#39149)

PR Close angular#39149

Author: alex-okrushko

CODE_OF_CONDUCT.md

@@ -3,7 +3,7 @@
 
 As contributors and maintainers of the Angular project, we pledge to respect everyone who contributes by posting issues, updating documentation, submitting pull requests, providing feedback in comments, and any other activities.
 
-Communication through any of Angular's channels (GitHub, Gitter, IRC, mailing lists, Google+, Twitter, etc.) must be constructive and never resort to personal attacks, trolling, public or private harassment, insults, or other unprofessional conduct.
+Communication through any of Angular's channels (GitHub, Discord, Gitter, IRC, mailing lists, Twitter, etc.) must be constructive and never resort to personal attacks, trolling, public or private harassment, insults, or other unprofessional conduct.
 
 We promise to extend courtesy and respect to everyone involved in this project regardless of gender, gender identity, sexual orientation, disability, age, race, ethnicity, religion, or level of experience. We expect anyone contributing to the Angular project to do the same.
 

CONTRIBUTING.md

@@ -32,7 +32,7 @@ Stack Overflow is a much better place to ask questions since:
 
 To save your and our time, we will systematically close all issues that are requests for general support and redirect people to Stack Overflow.
 
-If you would like to chat about the question in real-time, you can reach out via [our gitter channel][gitter].
+If you would like to chat about the question in real-time, you can reach out via [our Discord server][discord].
 
 
 ## <a name="issue"></a> Found a Bug?
@@ -382,7 +382,7 @@ The following documents can help you sort out issues with GitHub accounts and mu
 [corporate-cla]: http://code.google.com/legal/corporate-cla-v1.0.html
 [dev-doc]: https://github.com/angular/angular/blob/master/docs/DEVELOPER.md
 [github]: https://github.com/angular/angular
-[gitter]: https://gitter.im/angular/angular
+[discord]: https://discord.gg/angular
 [individual-cla]: http://code.google.com/legal/individual-cla-v1.0.html
 [js-style-guide]: https://google.github.io/styleguide/jsguide.html
 [jsfiddle]: http://jsfiddle.net

README.md

@@ -1,4 +1,5 @@
 [![CircleCI](https://circleci.com/gh/angular/angular/tree/master.svg?style=shield)](https://circleci.com/gh/angular/workflows/angular/tree/master)
+[![Discord](https://img.shields.io/discord/463752820026376202.svg?label=&logo=discord&logoColor=ffffff&color=7389D8&labelColor=6A7EC2)](https://discord.gg/angular)
 [![Join the chat at https://gitter.im/angular/angular](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/angular/angular?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 [![npm version](https://badge.fury.io/js/%40angular%2Fcore.svg)](https://www.npmjs.com/@angular/core)
 

aio/content/navigation.json

@@ -116,7 +116,7 @@
               "title": "Component Lifecycle",
               "tooltip": "Angular calls lifecycle hook methods on directives and components as it creates, changes, and destroys them."
             },
-            { 
+            {
               "url": "guide/view-encapsulation",
               "title": "View Encapsulation",
               "tooltip": "Describes how component CSS styles are encapsulated into a component's view."
@@ -1009,6 +1009,11 @@
           "title": "Stack Overflow",
           "tooltip": "Stack Overflow: where the community answers your technical Angular questions."
         },
+        {
+          "url": "https://discord.gg/angular",
+          "title": "Join Discord",
+          "tooltip": "Join the discussions at Angular Community Discord server."
+        },
         {
           "url": "https://gitter.im/angular/angular",
           "title": "Gitter",