Fix typo

Author: wooorm

readme.md

@@ -39,7 +39,7 @@ Check if the given value is a [**heading**][spec] [element][].
 
 ## Contribute
 
-See [`contribute.md` in `syntax-tree/hast`][contribute] for ways to get
+See [`contributing.md` in `syntax-tree/hast`][contributing] for ways to get
 started.
 
 This organisation has a [Code of Conduct][coc].  By interacting with this
@@ -71,6 +71,6 @@ repository, organisation, or community you agree to abide by its terms.
 
 [spec]: https://html.spec.whatwg.org/#heading-content
 
-[contribute]: https://github.com/syntax-tree/hast/blob/master/contributing.md
+[contributing]: https://github.com/syntax-tree/hast/blob/master/contributing.md
 
 [coc]: https://github.com/syntax-tree/hast/blob/master/code-of-conduct.md