README: add GitHub Sponsors link.

Let people know we support this now. Don't need a dedicated link because we have one at the top of the page.

README.md

@@ -57,7 +57,7 @@ Documentation is under the [Creative Commons Attribution license](https://creati
 ## Donations
 Homebrew is a non-profit project run entirely by unpaid volunteers. We need your funds to pay for software, hardware and hosting around continuous integration and future improvements to the project. Every donation will be spent on making Homebrew better for our users.
 
-Please consider a regular donation through Patreon:
+Please consider a regular donation through [GitHub Sponsors](https://github.com/sponsors/Homebrew) or [Patreon](https://www.patreon.com/homebrew):
 
 [![Donate with Patreon](https://img.shields.io/badge/patreon-donate-green.svg)](https://www.patreon.com/homebrew)