Update README.md

Author: chcost

README.md

@@ -50,7 +50,7 @@ You can try out some of CodeFlare features using the My Binder service.
 
 Click on a link below to try CodeFlare, on a sandbox environment, without having to install anything.
 
-[![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/project-codeflare/codeflare.git/main)
+[![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/project-codeflare/codeflare.git/master)
 
 ### Try on your laptop and scale on the cloud