Added license for ParallaxPagerTransformer

Added license for xgc1986/ParallaxPagerTransformer library which was mentioned as "Unknown License" earlier.

README.md

@@ -163,7 +163,7 @@ ViewPager
 ======================
 Name | License | Demo
 --- | --- | ---
-[ParallaxPagerTransformer](https://github.com/xgc1986/ParallaxPagerTransformer) | UnKnown | <img src="/art/ParallaxPagerTransformer.gif" width="49%">
+[ParallaxPagerTransformer](https://github.com/xgc1986/ParallaxPagerTransformer) | [Apache License V2](https://www.apache.org/licenses/LICENSE-2.0) | <img src="/art/ParallaxPagerTransformer.gif" width="49%">
 [ViewPagerTransforms](https://github.com/ToxicBakery/ViewPagerTransforms) | [Apache License V2](https://www.apache.org/licenses/LICENSE-2.0) | <img src="/art/ViewPagerTransforms.gif" width="49%">
 [CircleIndicator](https://github.com/ongakuer/CircleIndicator) | [MIT](https://opensource.org/licenses/MIT) | <img src="/art/CircleIndicator.gif" width="49%">
 [Android ViewPagerIndicator](https://github.com/JakeWharton/ViewPagerIndicator) | [Apache License V2](https://www.apache.org/licenses/LICENSE-2.0) | <img src="/art/Android-ViewPagerIndicator.png" width="100%">