Add Contribute section to readme.md

Author: wooorm

readme.md

@@ -30,6 +30,7 @@ documents. The latest released version is [`1.0.0`][latest].
     *   [Source](#source)
     *   [TextNode](#textnode)
 *   [Related](#related)
+*   [Contribute](#contribute)
 *   [License](#license)
 
 ## List of Utilities
@@ -161,6 +162,20 @@ interface TextNode < Text {
 *   [hast][]
 *   [mdast][]
 
+## Contribute
+
+**nlcst** is built by people just like you!  Check out
+[`contribute.md`][contribute] for ways to get started.
+
+This project has a [Code of Conduct][coc].  By interacting with this repository,
+organisation, or community you agree to abide by its terms.
+
+Want to chat with the community and contributors?  Join us in [Gitter][chat]!
+
+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!
+
 ## License
 
 MIT © Titus Wormer
@@ -192,3 +207,11 @@ MIT © Titus Wormer
 [hast]: https://github.com/syntax-tree/hast
 
 [mdast]: https://github.com/syntax-tree/mdast
+
+[contribute]: contributing.md
+
+[coc]: code-of-conduct.md
+
+[ideas]: https://github.com/syntax-tree/ideas
+
+[chat]: https://gitter.im/wooorm/retext