Guys .... Whenever you apply for GC notes, the the "Review of additional documents" status does change to "We need more documents to continue processing your application. We will send you a message with more details."
I called the CIC helpline and asked for the reason for same. And they explained that these status are kind of designed to provide information in both ways, ie from CIC side as well as the applicant / representative side.
The GC notes are generated from a case management system which is used by different ministries in Canada. Citizenship & Immigration in Canada (CIC) being just one of the ministry (in list of many) to use the case management system. So when you apply for GC notes, you are demanding the additional documents from CIC. Hence the status shows more documents needed to continue processing.
FYI .... the processing time for your application in CIC .... IS NOT AFFECTED .... because you have applied for GC notes. As this case management system & notes generation runs parallel to the application processing.