README.md: Fix EditDevDocs URL

README.md

@@ -122,4 +122,4 @@ You want to contribute to Pico? We really appreciate that! You can help make Pic
 [ContributionGuidelines]: https://github.com/picocms/Pico/blob/master/CONTRIBUTING.md
 [EditInlineDocs]: https://github.com/picocms/Pico/edit/master/content-sample/index.md
 [EditUserDocs]: https://github.com/picocms/Pico/tree/gh-pages/_docs
-[EditDevDocs]: https://github.com/picocms/Pico/tree/gh-pages/_plugin-dev
+[EditDevDocs]: https://github.com/picocms/Pico/tree/gh-pages/_development