Updated CONTRIBUTORS.md to include mxnet-label-bot (apache#13048)

* Updated CONTRIBUTERS.md to include label-bot

* Created section for label bot and included wiki page

* Moved Label Bot section in CONTRIBUTORS.md file to a more convenient location

* Retriggering

CONTRIBUTORS.md

@@ -58,6 +58,7 @@ who are willing to help maintaining and leading the project. Committers come fro
 
 New committers will be proposed by current committers, with support from more than two of current committers.
 
+
 List of Contributors
 --------------------
 * [Full List of Contributors](https://github.com/apache/incubator-mxnet/graphs/contributors)
@@ -189,3 +190,10 @@ List of Contributors
 * [Denisa Roberts](https://github.com/D-Roberts)
 * [Dick Carter](https://github.com/DickJC123)
 * [Rahul Padmanabhan](https://github.com/rahul3)
+
+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]
+  - For further details: [My Wiki Page](https://cwiki.apache.org/confluence/display/MXNET/Machine+Learning+Based+GitHub+Bot)