fix : add instructions for resolving the support library not found error (#810)

Author: harshithdwivedi

README.md

@@ -136,6 +136,22 @@ compile "com.android.support:appcompat-v7:$BAR"
 compile "com.android.support:palette-v7:$BAR"
 ```
 
+NOTE :
+Starting version 25.4.0, support libraries are now available through [Google's Maven repository](https://developer.android.com/studio/build/dependencies.html#google-maven), so ensure that you have that added to your project's repositories.
+
+Open the `build.gradle` file for your project and modify it as following,
+
+```
+allprojects {
+    repositories {
+        maven {
+            url "https://maven.google.com"
+        }
+        jcenter()
+    }
+}
+```
+
 ## Sample App
 
 There is a sample app in the `app/` directory that demonstrates most