Update README.md

Author: squti

README.md

@@ -1 +1,48 @@
-# Guru
+# Guru
+
+Guru is a handy and powerful library to work with key-value storages in Android
+<p align="center">
+  <img width="500" height="170" src="https://raw.githubusercontent.com/squti/Guru/master/static/guru_logo.png">
+</p>
+
+
+This library is an efficient and super easy way to use Android Shared Preferences without complexity and supports all of it functionalities.
+
+
+### Usage
+There is no need to initialize or config Guru. Just call it methods directly anywhere.
+
+```java
+// To save String
+Guru.putString("KEY", "value");
+
+```
+
+```java
+// To get String
+// default value returns if the key doesn't exist
+Guru.getString("KEY", "default value");
+
+```
+That's it !
+
+This example shows how to put and get a string. You can use other methods to work with other data types.
+### Configuration
+The default Preferences file name is `APPLICATION_ID.Default_App_Preference` <br/>
+(example: com.github.squti.guru.Default_App_Preference)<br/>
+And the default Preferences mode is `MODE_PRIVATE`
+
+But you can change them using `GuruConfig`, in your Application class in the `#onCreate()` method.
+```java
+    @Override
+    public void onCreate() {
+        super.onCreate();
+        GuruConfig.initDefault(new GuruConfig.Builder()
+                .setFileName("guru_preference")
+                .setMode(Context.MODE_PRIVATE)
+                .build());       
+        //....
+    }
+```
+_Note: You don't need to define `GuruConfig` and the library will apply
+default configuration._