Add Acknowledgments section to readme.md

Author: wooorm

readme.md

@@ -48,6 +48,7 @@ documents. The latest released version is [`2.1.0`][latest].
 *   [List of Utilities](#list-of-utilities)
 *   [Related](#related)
 *   [Contribute](#contribute)
+*   [Acknowledgments](#acknowledgments)
 
 ## AST
 
@@ -962,6 +963,27 @@ Have an idea for a cool new utility or tool?  That’s great!  If you want
 feedback, help, or just to share it with the world you can do so by creating
 an issue in the [`syntax-tree/ideas`][ideas] repository!
 
+## Acknowledgments
+
+The initial release of this project was authored by
+[**@wooorm**](https://github.com/wooorm).
+
+Special thanks to [**@eush77**](https://github.com/eush77) for their work,
+ideas, and incredibly valuable feedback!
+
+Thanks to
+[**@anandthakker**](https://github.com/anandthakker),
+[**@BarryThePenguin**](https://github.com/BarryThePenguin),
+[**@izumin5210**](https://github.com/izumin5210),
+[**@jasonLaster**](https://github.com/jasonLaster),
+[**@justjake**](https://github.com/justjake),
+[**@KyleAMathews**](https://github.com/KyleAMathews),
+[**@Rokt33r**](https://github.com/Rokt33r),
+[**@rhysd**](https://github.com/rhysd),
+[**@Sarah-Seo**](https://github.com/Sarah-Seo),
+[**@sethvincent**](https://github.com/sethvincent), and
+[**@simov**](https://github.com/simov) for contributing commits since!
+
 <!-- Definitions -->
 
 [logo]: https://cdn.rawgit.com/syntax-tree/mdast/6205835/logo.svg