docs: Fixed command to open multi_keyring.html in example-browser (aws#220)

Author: saipavan-narasaraj

modules/example-browser/Readme.md

@@ -79,7 +79,7 @@ open html/aes_simple.html
 
 ```
 npm run example-multi-keyring
-open html/multi_keyring_simple.html
+open html/multi_keyring.html
 ```
 
 ## License