Update README.md

Author: cesardeazevedo

README.md

@@ -41,12 +41,11 @@ android/app/build.gradle
 
 
 ```diff
--    compileSdkVersion 23
-+    compileSdkVersion 25
+    compileSdkVersion 26
 
     dependencies {
         compile fileTree(dir: "libs", include: ["*.jar"])
-        compile "com.android.support:appcompat-v7:23.0.1"
+        compile "com.android.support:appcompat-v7:26.1.0"
         compile "com.facebook.react:react-native:+"  // From node_modules
 +       compile project(':react-native-collapsing-toolbar')
 +       compile project(':react-native-nested-scroll-view')