Adds link to Content Security Policy doc (#4581)

Author: compulim

README.md

@@ -7,9 +7,11 @@
 [![npm version](https://badge.fury.io/js/botframework-webchat.svg)](https://badge.fury.io/js/botframework-webchat)
 [![Build Status](https://fuselabs.visualstudio.com/BotFramework-WebChat/_apis/build/status/BotFramework-WebChat-daily?branchName=main)](https://fuselabs.visualstudio.com/BotFramework-WebChat/_build/latest?definitionId=498&branchName=main)
 
-This repository contains code for the Bot Framework Web Chat component. The Bot Framework Web Chat component is a highly-customizable web-based client for the Bot Framework V4 SDK. The Bot Framework SDK v4 enables developers to model conversation and build sophisticated bot applications.
+This repository contains code for the Bot Framework Web Chat component. The Bot Framework Web Chat component is a highly-customizable web-based client for the Bot Framework v4 SDK. The Bot Framework SDK v4 enables developers to model conversation and build sophisticated bot applications.
 
-This repo is part of the [Microsoft Bot Framework](https://github.com/microsoft/botframework) - a comprehensive framework for building enterprise-grade conversational AI experiences.
+This repository is part of the [Microsoft Bot Framework](https://github.com/microsoft/botframework) - a comprehensive framework for building enterprise-grade conversational AI experiences.
+
+Web Chat supports [Content Security Policy (CSP)](https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP). Web developers are recommended to enable CSP to improve security and protect conversations. You can read more about CSP in [this article](https://github.com/microsoft/BotFramework-WebChat/blob/main/docs/CONTENT_SECURITY_POLICY.md).
 
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