Update Libraries-used.md

Author: nicolas-raoul

android/Libraries-used.md

@@ -16,7 +16,7 @@
 * [SLF4J][17]
 * [Logback][18]
 * [Butterknife][19]
-* [OKHttp][20]
+* [OkHttp][20]
 * [Okio][21]
 * [RxJava][22]
 * [RxBinding][23]
@@ -62,4 +62,4 @@
 [32]: https://github.com/nhaarman/mockito-kotlin
 [33]: https://developer.android.com/training/testing/espresso/
 [34]: https://github.com/square/leakcanary
-[35]: https://developer.android.com/topic/libraries/support-library/
+[35]: https://developer.android.com/topic/libraries/support-library/