New minor updates to Labs 3a & 3b

Both Labs 3a and 3b have been updated with minor clarifications to make the experience smoother for students.

In 3a, the lead assignment template names, subjects, and body text were tweaked to make them more typical and more consistent across the templates to reduce student mistakes. Some images were relocated to improve comprehension and another image was added for clarification. A couple of instances of awkward wording were also improved.

In 3b, steps 101-103 (adding a lead record via API) were edited and an overlay image was added to prevent student mistakes/confusion.

As always, the updates have been made to the files in place so when you download them now, they will be the new improved version. Here's the link to that same Google Drive folder containing all the lab PDFs for students.