Update README.md

update default branch name

Author: TimidRobot

README.md

@@ -61,7 +61,7 @@ If you are using a paid plan, you can do a one-click deploy with the button belo
 
 [![Deploy to Vercel](https://vercel.com/button)](https://vercel.com/new/project?template=vercel/og-image)
 
-Once you have an image generator that sparks joy, you can setup [automatic GitHub](https://vercel.com/github) deployments so that pushing to master will deploy to production! 🚀
+Once you have an image generator that sparks joy, you can setup [automatic GitHub](https://vercel.com/github) deployments so that pushing to main will deploy to production! 🚀
 
 ## Credits