Add CONTRIBUTING.md
Add CONTRIBUTING.md

- Add requirements for debian hosts
- Add section that explains how to add new docs.

healthchecks/healthchecks,healthchecks/healthchecks,iphoting/healthchecks,healthchecks/healthchecks,iphoting/healthchecks,healthchecks/healthchecks,iphoting/healthchecks,iphoting/healthchecks