This PR adds two How To docs demonstrating how to use the probability and percentile based decision points in #930 to incorporate EPSS scoring into SSVC decision models. Two approaches are shown:

1. Using EPSS probabilties alongside KEV and CVSS Exploit Maturity to choose an SSVC Exploitation value
2. Using EPSS percentiles to amplify the output of the SSVC Deployer Decision Model

Some incidental code in support of the tutorials is also added.

Screenshots of the three pages are given below, along with print-to-PDF renderings of the pages. Note that the PDFs expand all collapsed admonition boxes in the page so they appear quite a bit longer than they do when rendered on screen. (All the JSON notation boxes are collapsed on-screen, for example.)

Screenshot	PDF
	EPSS → SSVC Intro - SSVC_ Stakeholder-Specific Vulnerability Categorization.pdf
	EPSS Probability as input to Exploitation - SSVC_ Stakeholder-Specific Vulnerability Categorization.pdf
	EPSS Percentiles as an Amplifier - SSVC_ Stakeholder-Specific Vulnerability Categorization.pdf

Copilot Summary

This pull request introduces new documentation and code improvements to support using EPSS (Exploit Prediction Scoring System) data with SSVC (Stakeholder-Specific Vulnerability Categorization). The main changes include the addition of comprehensive how-to guides for integrating EPSS scores and percentiles into SSVC decision models, updates to the navigation structure, and enhancements to the codebase to make available various probability and quantile-based decision points.

Documentation enhancements:

• Added an introductory guide and two detailed how-to guides on using EPSS probability scores and percentiles within SSVC decision models, including practical examples and decision table diagrams. [1] [2] [3]
• Updated the navigation (mkdocs.yml) to include the new EPSS documentation section and its subpages.

Decision point code improvements:

• Added DECISION_POINTS dictionaries to both probability and quantiles modules, making it easier to access and enumerate available decision points in code and documentation. [1] [2]
• Updated the definition of the "Probability Scale in 5 weighted levels, ascending" decision point to reference its NIST source for clarity and traceability. [1] [2]

Example module additions:

• Introduced a new example decision point module and a base class for example decision points, laying the groundwork for illustrating custom or sample decision logic. [1] [2]