Added Readme.md in docs folder with instructions of how to generate sdk documentation (#203)

* Added Readme.md to generate java docs

* Updated docs/readme.md instructions to generate documentations

Author: mnoman09

docs/readme.md

@@ -0,0 +1,15 @@
+# Generate Code Documentation
+### Steps
+
+* Checkout **master** branch.		
+* Open project in **Android Studio**.
+* Go to **Tools -> Generate JavaDoc**
+* Make sure **Generate JavaDoc scope -> Custom Scope** is checked.
+* Click on three dotted icon to make custom scope.
+* Give name **Custom_Docs**.
+* Copy and paste following regex: **`!test:*..*&&!lib:*..*&&!src[test-app]:*..*`** into **Pattern** and click **OK**.
+* Uncheck **Include test sources**.
+* Select **Output Directory**.
+* Click **OK**.
+* This will generate HTML documentation in given **Output Directory**.
+* Browse **Output Directory/index.html** in browser.