Update README.md

Author: RemiixInc

README.md

@@ -4,6 +4,6 @@ Serverless API to take screenshots of websites with Puppeteer.
 ## Example
 https://s.vercel.app/api?url=https://google.com&width=1280&height=720
 
-### Deploy your own screenshot API for free:
+**Deploy your own screenshot API for free:**
 
 [![Deploy with Vercel](https://vercel.com/button)](https://vercel.com/new/git/external?repository-url=https%3A%2F%2Fgithub.com%2FRemiixInc%2Fscreenshot)