Removed placeholder folders that do not actually contain runtimes.

spine-js/README.md

@@ -1,3 +0,0 @@
-# spine-js
-
-spine-js has been replaced by [spine-ts](../spine-ts).

spine-threejs/README.md

@@ -1,3 +0,0 @@
-# spine-threejs
-
-spine-threejs has been replaced by [spine-ts THREE.JS backend](../spine-ts).

spine-tk2d/README.md

@@ -1,3 +0,0 @@
-# spine-tk2d
-
-The spine-tk2d runtime has been replaced by [spine-unity](../spine-unity). You may use spine-unity with [2D Toolkit](http://www.2dtoolkit.com/).