add step for instructions

Author: sdgilley

articles/machine-learning/how-to-create-labeling-projects.md

@@ -161,6 +161,7 @@ Use these steps to add one or more labels to a project:
     * Start over, removing all existing labels.  Choose this option if you want to wipe out all existing labels so that the full set can be used to tag all images.
     * Start over, keeping all existing labels.  Choose this option to mark all data as unlabeled, but keep the existing labels as a default tag for images that had been labeled.
     * Continue, keeping all existing labels. Choose this option to keep all data already labeled as is, and use the new label only for data not yet classified.
+1. Modify your instructions page as necessary for the new label(s).
 1. Once you have added all new labels, at the top of the page select **Start**  to restart the project.  
 
 ## Export the labels