Fix typo

readme.md

@@ -81,7 +81,7 @@ the node (and the parent, when given).
 
 ## 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
@@ -115,6 +115,6 @@ repository, organisation, or community you agree to abide by its terms.
 
 [mdast-util-assert]: https://github.com/syntax-tree/mdast-util-assert
 
-[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