Mostly minor Lab 3a/3b updates w/one notable deliverable alteration & added step

Both labs 3a and 3b have been updated with mostly minor fixes to typos, improved screencaps, etc with one notable alteration to 3a:

One new step has been added at the very end (Step 158) to take fuller advantage of the opportunity to learn CRM functionality–students move a lead from Open - Not Contacted to Working - Contacted after confirming receipt of an email to that lead. Students will see this depicted in color-changes to those two stages in the "Sales Path" as:

and this is an alteration to that screencap deliverable (Checkpoint 4) that could be easily added to the rubric to ensure they did the new last step though it is not especially consequential–the purpose is really just to take full advantage of the context that the previous steps have led to at that point. Now students get a chance to see the fuller CRM functionality available.