[TASK] Update contribution walkthrough link

The contribution walkthrough has been moved from the
wiki to docs.typo3.org

Change-Id: I683bfad410aa75a1dab7fee91b7f0b3cee60070d
Resolves: #77423
Releases: master, 7.6
Reviewed-on: https://review.typo3.org/49505


Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>

CONTRIBUTING.md

@@ -13,7 +13,7 @@ If you like to contribute to our [documentation][5], use the "Edit me on GitHub"
  in the top right of each manual or reference or just make a pull request in any of the repositories
  that can be found in the TYPO3 [documentation team GitHub organisation][6].
 
-[1]: https://wiki.typo3.org/Contribution_Walkthrough_Tutorials
+[1]: https://docs.typo3.org/typo3cms/ContributionWorkflowGuide/
 [2]: https://git.typo3.org/Packages/TYPO3.CMS.git
 [3]: https://review.typo3.org/#/q/project:Packages/TYPO3.CMS,n,z
 [4]: https://github.com/TYPO3/TYPO3.CMS