Hi I just stumbled on this post and I happen to be gathering information on training up one of my employees so thought I would share.

Check out the following learning LXPs at this site: https://nowlearning.service-now.com/lxp
Knowledge Management on the Now Platform
Knowledge Management (KM) Fundamentals
Knowledge Management (KM) Implementation
Knowledge Management: Use Knowledge (Paris)
Mobile: Create an Application (Rome)
Rome Delta – Certified System Administrator
Rome Delta – Certified Application Specialist – Performance Analytics

PATH 
Incident Management on the Now Platform (Paris)
Problem Management on the Now Platform (Paris)
Change Management on the Now Platform (Paris)
Knowledge Management on the Now Platform (Paris)
Customer Service Management on the Now Platform (Paris)

Now dealing with servicenow roles, groups & ACLs/permissions is like a onion within servicenow every time I understand a layer I found there are many more.  So it's a bit of learning development and system architecture to fully get a handle on all knowledge aspects of servicenow.  I've been on a little adventure diving as deep as I can sadly after my Idea for migrating all knowledge permissions to the knowledge_admin was not consider.  It got "Unlikely to implement" so I've been peeling back the layers when time allows for the past 2 months so far and I know there is much more to go.  As my main focus right now is all the internal permission I have yet to touch external needed permissions for customer facing articles.  The saving grace is the ability to download a servicenow Dev and to be able to go to town on figuring things out. Do not sleep on that feature of service now as it's very powerful for getting hands on experience before doing stuff in your production.  Well hope this helps some people with more knowledge training but i would highly recommend also looking at the learning on acls and more.  Take care.