Support debugging XSpec and Schematron bugs

[danielnaab]

Extended Description
As a knowledgable user or internal FedRAMP stakeholder, I would like to inspect the XSpec and Schematron for the validations, so I can study the logic and determine if there is a bug that requires fixing.

Context: when browsing the rules in the web documentation, a link to the corresponding lines of code on Github would aid the user in tracking down where the rule resides and how it is structured. For instance, a rule could include a link to the corresponding assertion, eg: https://github.com/GSA/fedramp-automation/blob/master/src/validations/rules/ssp.sch#L545-L551

Acceptance Criteria

• Docs link to Schematron assertion on Github
• Docs link to XSpec scenario on Github

Definition of Done

• Acceptance criteria met
• Unit test coverage of our code > 95%
• Automated code quality checks passed
• Security reviewed and reported
• Reviewed against plain language guidelines
• Code must be self-documenting
• No local tech debt
• Load/performance tests passed – needs to be created/automated
• Documentation updated
• Architectural Decision Record completed as necessary for significant design choices
• PR reviewed & approved
• Source code merged