README formatting tweak

Author: bvaughn

README.md

@@ -2,9 +2,9 @@
 
 `react-window` is a component library that helps render large lists of data quickly and without the performance problems that often go along with rendering a lot of data. It's used in a lot of places, from React DevTools to the Replay browser.
 
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+## Sponsors
 
-### If you like this project, 🎉 [become a sponsor](https://github.com/sponsors/bvaughn/) or ☕ [buy me a coffee](http://givebrian.coffee/).
+If you like this project, 🎉 [become a sponsor](https://github.com/sponsors/bvaughn/) or ☕ [buy me a coffee](http://givebrian.coffee/).
 
 The following wonderful companies have sponsored react-window: