Add clickable start course button to README

Updated README to include a clickable start course button.

Author: WirelessLife

Getting-Started-with-GitHub-Copilot/README.md

@@ -42,7 +42,7 @@ By the end of this module, you'll be able to:
 
 Create your own copy of the exercise repository:
 
-- **Copy exercise repository**: https://github.com/new?template_owner=skills&template_name=getting-started-with-github-copilot&owner=%40me&name=skills-getting-started-with-github-copilot&description=Exercise:+Get+started+using+GitHub+Copilot&visibility=public
+[![start-course](https://user-images.githubusercontent.com/1221423/235727646-4a590299-ffe5-480d-8cd5-8194ea184546.svg)] (https://github.com/new?template_owner=skills&template_name=getting-started-with-github-copilot&owner=%40me&name=skills-getting-started-with-github-copilot&description=Exercise:+Get+started+using+GitHub+Copilot&visibility=public)
 
 Then wait for setup automation to complete and refresh the page.