Update docs/assignments/week18.md, docs/images/week18/cnc_bottom.jpg,...

Update docs/assignments/week18.md, docs/images/week18/cnc_bottom.jpg, docs/images/week18/cnc_top_1.jpg, docs/images/week18/cnc_top_2.jpg, docs/images/week18/cnc_top_3.jpg, docs/images/week18/cnc_top_4.jpg, docs/images/week18/top_cnc_v1.jpg, docs/images/week18/top_surfacing_cnc_v1.jpg, docs/images/week18/bottom_cnc_v1.jpg files
1 job for jonah.marrs-master-patch-17720 in 49 seconds (queued for 2 seconds)
latest
Status Name Job ID Coverage
  Test
passed test #450864

00:00:49