Add OSS sponsorship link to README

README.md

@@ -168,3 +168,16 @@ some caveats which will need accommodations:
 ## Contributing
 
 Visit our [contribution guidelines](https://github.com/oddbird/popover-polyfill/blob/main/CONTRIBUTING.md).
+
+## Sponsor OddBird's OSS Work
+
+At OddBird, we love contributing to the languages & tools developers rely on. 
+We're currently working on polyfills 
+for new Popover & Anchor Positioning functionality, 
+as well as CSS specifications for functions, mixins, and responsive typography. 
+Help us keep this work sustainable 
+and centered on your needs as a developer! 
+We display sponsor logos and avatars 
+on our [website](https://www.oddbird.net/polyfill/#popover-polyfill).
+
+[Sponsor OddBird's OSS Work](https://opencollective.com/oddbird-open-source)