Usage:
Add functionality adds labels specified to the list of labels:
@mxnet-label-bot add [comma separated labels]
@mxnet-label-bot add [Good First Issue, Doc]
Remove functionality removes labels specified from the list of labels:
@mxnet-label-bot remove [comma separated labels]
@mxnet-label-bot remove [bug, question]
Update functionality updates the labels of the issue to only the labels specified in the list:
**Warning** : This removes all previous labels on the repo:
@mxnet-label-bot update [comma separated labels]
...