docs: fix links

Author: honzajavorek

CONTRIBUTING.md

@@ -41,6 +41,6 @@ The test suite uses the [Python hooks](https://github.com/apiaryio/dredd-hooks-p
 1.  Generalize the changed (or added) feature files with placeholders, comment-out the code examples, and copy the files over to this repository. Add missing test steps implementations to the `steps.js`. Create a Pull Request.
 1.  Make sure the smoke test passes under the Pull Request.
 1.  Merge the Pull Request and let Semantic Release to produce a new version of the test suite package.
-1.  Go to Python hooks repository and [upgrade](#upgrading) the test suite package there. Remove any local `steps.js` as the necessary steps should already be implemented in the new version of the test suite package.
-1.  Go to Ruby hooks repository and [upgrade](#upgrading) the test suite package there.
+1.  Go to Python hooks repository and [upgrade](README.md#upgrading) the test suite package there. Remove any local `steps.js` as the necessary steps should already be implemented in the new version of the test suite package.
+1.  Go to Ruby hooks repository and [upgrade](README.md#upgrading) the test suite package there.
 1.  Go to all remaining repositories with hooks handlers and issue Pull Requests for the maintainers which help them to kick-off the upgrade. It's okay if they're incomplete, their purpose is to advertise the changes, to initiate the upgrade, and to be helpful to the maintainers.