Enable minify by using proguard-rules

Fix issue in proguard config related to this bug -> facebook/react-native#11891

Author: jonatansalas

android/app/build.gradle

@@ -80,7 +80,7 @@ def enableSeparateBuildPerCPUArchitecture = false
 /**
  * Run Proguard to shrink the Java bytecode in release builds.
  */
-def enableProguardInReleaseBuilds = false
+def enableProguardInReleaseBuilds = true
 
 android {
     compileSdkVersion 25

android/app/proguard-rules.pro

@@ -50,6 +50,8 @@
 
 -dontwarn com.facebook.react.**
 
+-dontwarn com.facebook.fbui.textlayoutbuilder.proxy.StaticLayoutProxy
+
 # okhttp
 
 -keepattributes Signature