Conversion to markdown (backend development) (#1608)
Conversion to markdown (backend development) (#1608)

Other minor changes:
* "2.4 Visualization" changed to "1.4 Visualization"
* Removed colon at the end of some of the headers
jxwang16/c4sg-web,jxwang16/c4sg-web,jxwang16/c4sg-web