update session 4 for Process Planning additions

[lcbw]

updating slides with pipeline presentation materials made by TMarr for clarity

[JeremyZoss]

Looks good. I'm squashing commits to reduce the number of minor fixup commits. Although these slide updates contained minor fixes to several sessions, the primary update was to replace the Descartes deep-dive in Basic Training Session 4 to a broader overview of motion planners in ROS.