Fix typo

Author: wooorm

readme.md

@@ -132,7 +132,7 @@ variable this plugin runs, otherwise it’s a noop.
 
 ## Contribute
 
-See [`contribute.md` in `unifiedjs/unified`][contribute] for ways to get
+See [`contributing.md` in `unifiedjs/unified`][contributing] for ways to get
 started.
 
 This organisation has a [Code of Conduct][coc].  By interacting with this
@@ -164,6 +164,6 @@ repository, organisation, or community you agree to abide by its terms.
 
 [retext]: https://github.com./retextjs/retext/blob/master/doc/plugins.md#list-of-plugins
 
-[contribute]: https://github.com./unifiedjs/unified/blob/master/contributing.md
+[contributing]: https://github.com./unifiedjs/unified/blob/master/contributing.md
 
 [coc]: https://github.com./unifiedjs/unified/blob/master/code-of-conduct.md