readme: added support me

Author: dg

readme.md

@@ -42,3 +42,12 @@ composer require nette/utils
 - Nette Utils 3.1 is compatible with PHP 7.1 to 8.0
 - Nette Utils 3.0 is compatible with PHP 7.1 to 8.0
 - Nette Utils 2.5 is compatible with PHP 5.6 to 8.0
+
+[Support Me](https://github.com/sponsors/dg)
+--------------------------------------------
+
+Do you like Nette Utils? Are you looking forward to the new features?
+
+[![Buy me a coffee](https://files.nette.org/icons/donation-3.svg)](https://github.com/sponsors/dg)
+
+Thank you!