Update web-platform-tests URLs

CONTRIBUTING.md

@@ -24,8 +24,8 @@ feature, you can remove yourself with the above syntax.
 # Tests
 
 For normative changes, a corresponding
-[web-platform-tests](https://github.com/w3c/web-platform-tests) PR is highly appreciated. Typically,
+[web-platform-tests](https://github.com/web-platform-tests/wpt) PR is highly appreciated. Typically,
 both PRs will be merged at the same time. Note that a test change that contradicts the spec should
 not be merged before the corresponding spec change. If testing is not practical, please explain why
-and if appropriate [file an issue](https://github.com/w3c/web-platform-tests/issues/new) to follow
+and if appropriate [file an issue](https://github.com/web-platform-tests/wpt/issues/new) to follow
 up later. Add the `type:untestable` or `type:missing-coverage` label as appropriate.

motion-1/Overview.bs

@@ -13,7 +13,7 @@ Editor: Dirk Schulze, Adobe Systems Inc., dschulze@adobe.com, w3cid 51803
 Editor: Shane Stephens, Google, shanestephens@google.com, w3cid 47691
 Editor: Jihye Hong, LG Electronics, jh.hong@lge.com, w3cid 79168
 Editor: Eric Willigers, Google, ericwilligers@google.com, w3cid 67534
-Test Suite: https://github.com/w3c/web-platform-tests/tree/master/css/motion-1
+Test Suite: https://github.com/web-platform-tests/wpt/tree/master/css/motion
 Abstract: Motion path allows authors to position any graphical object and animate it along an author specified path.
 </pre>