Add collective badges

Author: wooorm

readme.md

@@ -4,6 +4,9 @@
 [![Coverage][coverage-badge]][coverage]
 [![Downloads][downloads-badge]][downloads]
 [![Size][size-badge]][size]
+[![Sponsors][sponsors-badge]][collective]
+[![Backers][backers-badge]][collective]
+[![Chat][chat-badge]][chat]
 
 [**unist**][unist] utility to create a new [tree][] by mapping all [node][]s
 with the given function.
@@ -131,6 +134,16 @@ abide by its terms.
 
 [size]: https://bundlephobia.com/result?p=unist-util-map
 
+[sponsors-badge]: https://opencollective.com/unified/sponsors/badge.svg
+
+[backers-badge]: https://opencollective.com/unified/backers/badge.svg
+
+[collective]: https://opencollective.com/unified
+
+[chat-badge]: https://img.shields.io/badge/join%20the%20community-on%20spectrum-7b16ff.svg
+
+[chat]: https://spectrum.chat/unified/syntax-tree
+
 [npm]: https://docs.npmjs.com/cli/install
 
 [license]: license