Improve readme.

README.md

@@ -7,6 +7,17 @@
 
 > Makes your GitHub notifications icon link to [Octobox](https://octobox.io) instead of GitHub.
 
+## Introduction
+
+[Octobox](https://octobox.io) is an awesome inbox-like entrypoint to GitHub notifications.
+Unfortunately, however, it does not integrate with the GitHub UI, meaning the GitHub notifications icon still links to the GitHub notifications page.
+
+This cross-browser web extension fixes that!
+While the notification icon still looks like before—including its status indicator—it now points to your Octobox.
+
+Once there, you can click one of your notifications to go to the according page on GitHub.
+In case you want to go back to the GitHub dashboard, the web extension injects a GitHub icon to the menu bar for you.
+
 ## Installation
 
 The Octobox Web Extension is available for [Google Chrome](https://chrome.google.com/webstore/detail/octobox-web-extension/efhkcafmbonnomnimilnephjgeccffdn) and [Mozilla Firefox](https://addons.mozilla.org/en-US/firefox/addon/octobox-web-extension/).