Add Description of Workflows in Contributing Guide

[ArielSAdamsNASA]

Checklist (Please check before submitting)

• I reviewed the Contributing Guide.
• I reviewed the cFS README.md file to see if the feature is in the major future work.
• I performed a cursory search to see if the feature request is relevant, not redundant, nor in conflict with other tickets.

Is your feature request related to a problem? Please describe.
Users may not know the purpose of each workflow we use.

Describe the solution you'd like
Provide a short description of each workflow.

Describe alternatives you've considered
N/A

Requester Info
Ariel Adams, ASRC Federal