readme manager initial setup (#209)

* readme manager initial setup

This PR makes the README ready to be managed by the readme manager. It adds custom comment tags to the readme, which are invisible when the README is rendered, but tell the readme manager where to insert and update content.

* Update README.md

+<!--BEGIN_BANNER_IMAGE--><!--END_BANNER_IMAGE-->
+
 # Android Kotlin SDK for LiveKit
 
+<!--BEGIN_DESCRIPTION-->
 Official Android Client SDK for [LiveKit](https://github.com/livekit/livekit-server). Easily add
 video & audio capabilities to your Android apps.
+<!--END_DESCRIPTION-->
 
 Table of Contents
 =================
@@ -227,3 +231,5 @@ protoc_platform=osx-x86_64
 
 1. Download webrtc sources from https://webrtc.googlesource.com/src
 2. Add sources to Android Studio by pointing at the `webrtc/sdk/android` folder.
+
+<!--BEGIN_REPO_NAV--><!--END_REPO_NAV-->