Update README.md

Author: antonmedv

README.md

@@ -45,6 +45,10 @@ Inspired by
 go get -u github.com/antonmedv/expr
 ```
 
+<a href="https://www.patreon.com/antonmedv">
+	<img src="https://c5.patreon.com/external/logo/become_a_patron_button@2x.png" width="160">
+</a>
+
 ## Documentation
 
 * See [![GoDoc](https://godoc.org/github.com/antonmedv/expr?status.svg)](https://godoc.org/github.com/antonmedv/expr) for developer documentation,