Update README.md (#5963)

Author: zxyanliu

README.md

@@ -150,7 +150,7 @@ We track functional issues and features asks for the Bot Framework SDK, tools an
 - [Analytics](#Analytics)
 
 ### Bot Framework Composer
-[Bot Framework Composer](https://github.com/microsoft/BotFramework-Composer/blob/stable/README.md) is an integrated development tool for developers and multi-disciplinary teams to build bots and conversational experiences with the Microsoft Bot Framework. Within this tool, you'll find everything you need to build a sophisticated conversational experience.
+[Bot Framework Composer](https://github.com/microsoft/BotFramework-Composer/blob/main/README.md) is an integrated development tool for developers and multi-disciplinary teams to build bots and conversational experiences with the Microsoft Bot Framework. Within this tool, you'll find everything you need to build a sophisticated conversational experience.
 
 ### Botkit
 [Botkit][100] is a developer tool and SDK for building chat bots, apps and custom integrations for major messaging platforms. Botkit bots `hear()` triggers, `ask()` questions and `say()` replies. Developers can use this syntax to build dialogs - now cross compatible with the latest version of Bot Framework SDK.