Updated the Instructions for use of the label bot

CONTRIBUTORS.md

@@ -191,10 +191,17 @@ List of Contributors
 * [Dick Carter](https://github.com/DickJC123)
 * [Rahul Padmanabhan](https://github.com/rahul3)
 * [Yuxi Hu](https://github.com/yuxihu)
+* [Harsh Patel](https://github.com/harshp8l)
 
 Label Bot
 ---------
 * [mxnet-label-bot](https://github.com/mxnet-label-bot)
-  - mxnet-label-bot provides users with the functionality to add labels from the repository to issues
-  - To use me, comment: @mxnet-label-bot add [specify label here]
+  - mxnet-label-bot provides users with the functionality to manage labels for Issues/Pull Requests on the repository
+  - To use me, comment:
+    - @mxnet-label-bot add [specify comma separated labels here]
+    - @mxnet-label-bot remove [specify comma separated labels here]
+    - @mxnet-label-bot update [specify comma separated labels here]  
+      (i.e. @mxnet-label-bot update [Bug, Python])
+
+  - Available label names which are supported: [Labels](https://github.com/apache/incubator-mxnet/labels)
   - For further details: [My Wiki Page](https://cwiki.apache.org/confluence/display/MXNET/Machine+Learning+Based+GitHub+Bot)