add cursor button (#68)

Author: julianduque

README.md

@@ -1,5 +1,6 @@
 # heroku-mcp-server
 
+[![Install MCP Server](https://cursor.com/deeplink/mcp-install-dark.svg)](https://cursor.com/install-mcp?name=heroku&config=eyJjb21tYW5kIjoibnB4IC15IEBoZXJva3UvbWNwLXNlcnZlciIsImVudiI6eyJIRVJPS1VfQVBJX0tFWSI6IjxZT1VSX0hFUk9LVV9BVVRIX1RPS0VOPiJ9fQ%3D%3D)
 [![smithery badge](https://smithery.ai/badge/@heroku/heroku-mcp-server)](https://smithery.ai/server/@heroku/heroku-mcp-server)
 
 > The Heroku Platform MCP Server works on Common Runtime, Cedar Private and Shield Spaces, and Fir Private Spaces.