[Pages][MVP] Add Jekyll front-matter to main INDEX.md files

[jacob-kraniak]

Description of the Enhancement

Goal
Make the most important navigation pages (home + category indexes) render nicely as standalone site pages with proper titles, headings, and future sidebar potential.

Tasks

• Add minimal YAML front-matter to:

  • docs/index.md (already copied from README)
  • documentation/INDEX.md
  • tools/_INDEX.md (consider renaming to INDEX.md per SOP consistency note)

• Example front-matter block (add at very top of each file):

---
layout: default   # or home if using Just the Docs
title: Documentation Overview
nav_order: 2      # controls sidebar order; 1 = home, higher = lower
---

For docs/index.md: title: "The Book of Secret Knowledge"
For documentation/INDEX.md: title: "Documentation & Learning Resources"
For tools/_INDEX.md: title: "Tools & Utilities"

• Keep all existing content below the front-matter.
• Test: After commit + Pages rebuild, visit e.g.,
• https://jacob-kraniak.github.io/the-book-of-secret-knowledge/documentation/INDEX/

Acceptance Criteria

• At least 3 files have front-matter added.
• Pages rebuild succeeds (no YAML errors).
• Titles appear in browser tab and page heading.
• Existing markdown tables/lists render correctly (TOOL-TABLE-SCHEMA tables should look good natively).

Notes

This is lightweight prep for Phase 2 sidebar/collection setup.
Avoid heavy changes — just front-matter for now.