chore(oauth2): start article

knowledge base/oauth2.md

@@ -0,0 +1,73 @@
+# OAuth 2.0
+
+TODO
+
+Intro
+
+<!-- Remove this line to uncomment if used
+## Table of contents <!-- omit in toc -->
+
+1. [TL;DR](#tldr)
+1. [Use OAuth 2.0 in an application](#use-oauth-20-in-an-application)
+1. [Further readings](#further-readings)
+   1. [Sources](#sources)
+
+## TL;DR
+
+<!-- Uncomment if used
+<details>
+  <summary>Setup</summary>
+
+```sh
+```
+
+</details>
+-->
+
+<!-- Uncomment if used
+<details>
+  <summary>Usage</summary>
+
+```sh
+```
+
+</details>
+-->
+
+<!-- Uncomment if used
+<details>
+  <summary>Real world use cases</summary>
+
+```sh
+```
+
+</details>
+-->
+
+## Use OAuth 2.0 in an application
+
+Refer [Setting up OAuth 2.0].
+
+## Further readings
+
+- [Website]
+- [Main repository]
+
+### Sources
+
+- [Setting up OAuth 2.0]
+
+<!--
+  Reference
+  ═╬═Time══
+  -->
+
+<!-- In-article sections -->
+<!-- Knowledge base -->
+<!-- Files -->
+<!-- Upstream -->
+[main repository]: https://github.com/project/
+[website]: https://website/
+[setting up oauth 2.0]: https://support.google.com/googleapi/answer/6158849
+
+<!-- Others -->