Updated README

Author: squidfunk

README.md

@@ -28,6 +28,10 @@
     src="https://img.shields.io/docker/pulls/squidfunk/mkdocs-material"
     alt="Docker Pulls"
   /></a>
+  <a href="https://github.com/sponsors/squidfunk"><img
+    src="https://img.shields.io/github/sponsors/squidfunk"
+    alt="Sponsors"
+  /></a>
 </p>
 
 <p align="center">