Fix typo

Author: wooorm

readme.md

@@ -61,7 +61,7 @@ end.  `null` is returned if the given value is neither `node`,
 
 ## Contribute
 
-See [`contribute.md` in `syntax-tree/unist`][contribute] for ways to get
+See [`contributing.md` in `syntax-tree/unist`][contributing] for ways to get
 started.
 
 This organisation has a [Code of Conduct][coc].  By interacting with this
@@ -95,6 +95,6 @@ repository, organisation, or community you agree to abide by its terms.
 
 [point]: https://github.com/syntax-tree/unist#point
 
-[contribute]: https://github.com/syntax-tree/unist/blob/master/contributing.md
+[contributing]: https://github.com/syntax-tree/unist/blob/master/contributing.md
 
 [coc]: https://github.com/syntax-tree/unist/blob/master/code-of-conduct.md