Optionally generate links to edit source documents in rendered SSP

[rahearn]

Story

As a devsecops engineer,
I would like to quickly navigate to the source markdown for a given SSPP section,
So that I can quickly update the correct spot in the source

Solution

Tasks

Beta Give feedback

1. add flag to ssp_data.yaml to control output
2. add config to ssp_data.yaml to control base URL of repo
3. hide links from PDF printing

Acceptance Criteria

• links for all sections lead to their source in github/gitlab
• links are hidden before printing, no matter if they are enabled in markdown or html