docs: add funding info

README.md

@@ -1,3 +1,6 @@
+
+[:heart: sponsor](https://github.com/sponsors/rbellens)
+
 # x509
 
 Dart library for parsing and working with X.509 certificates.
@@ -21,3 +24,12 @@ A simple usage example:
 Please file feature requests and bugs at the [issue tracker][tracker].
 
 [tracker]: https://github.com/appsup-dart/x509/issues
+
+
+
+## Sponsor
+
+Creating and maintaining this package takes a lot of time. If you like the result, please consider to [:heart: sponsor](https://github.com/sponsors/rbellens). 
+With your support, I will be able to further improve and support this project.
+Also, check out my other dart packages at [pub.dev](https://pub.dev/packages?q=publisher%3Aappsup.be).
+

pubspec.yaml

@@ -2,6 +2,8 @@ name: x509
 description: Dart library for parsing and working with X.509 certificates.
 version: 0.2.2
 homepage: https://github.com/appsup-dart/x509
+funding:
+ - https://github.com/sponsors/rbellens
 
 environment:
   sdk: '>=2.12.0 <3.0.0'