Add usage

Author: jcs090218

README.md

@@ -1,4 +1,13 @@
+[![License: GPL v3](https://img.shields.io/badge/License-GPL%20v3-blue.svg)](https://www.gnu.org/licenses/gpl-3.0)
+[![JCS-ELPA](https://raw.githubusercontent.com/jcs-emacs/badges/master/elpa/v/dashboard-bm.svg)](https://jcs-emacs.github.io/jcs-elpa/#/dashboard-bm)
+
 # dashboard-bm
 > Visual Bookmarks (bm.el) for Dashboard
 
+## Usage
 
+```elisp
+(setq dashboard-items '(..
+                        (bm . 10))  ; add this line
+                        ..)
+```