Fix blank enterprise-rollout section landing pages

[malston]

Problem

Every link under the Sections header on the Enterprise Claude Code Rollout landing page opened a blank page (reported for /enterprise-rollout/00-overview/, but all eight were affected).

Root cause

The 8 subsection _index.md files under content/enterprise-rollout/ contained only YAML front matter and no body. The Hugo Book theme renders the _index body in the main pane, so an empty body produces a blank page. The flat sections (guides, internals, perspectives) were unaffected -- they have body content and no nested subsections, so they were never exercised this way.

Fix

Give each subsection index a landing body:

• An H1 matching the section title.
• The one-line description already used for that section on the parent binder page (kept consistent).
• Weight-ordered links to the section's child articles, using relref shortcodes (matches the parent page's link style and is build-checked).

No --- horizontal-rule dividers in the new content, per STYLE-GUIDE.md.

Verification

• hugo --gc --minify builds clean (106 pages). Strict relref resolves every link -- a broken ref would fail the build.
• Confirmed the rendered pages now contain their child links: 00-overview/index.html has all four (executive-summary, architecture-overview, roi-framework, three-year-npv-worksheet); appendix/index.html has its three.

Note

The parent enterprise-rollout/_index.md uses --- dividers (pre-existing style-guide deviation) -- left untouched as out of scope for this fix.

[Copilot]

Pull request overview

This PR fixes blank landing pages for the nested enterprise-rollout/ subsections in the Hugo Book theme by adding body content to each subsection _index.md, so the main pane renders meaningful content instead of an empty page.

Changes:

• Added an H1 + short section summary to each enterprise-rollout/*/_index.md subsection landing page.
• Added weight-ordered child-article link lists using {{< relref ... >}} to ensure build-checked navigation from each landing page.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
content/enterprise-rollout/00-overview/_index.md	Adds landing content and relref links to Overview child pages.
content/enterprise-rollout/01-skill-gaps-and-market-opportunity/_index.md	Adds landing content and relref links to section child pages.
content/enterprise-rollout/02-phase-0-infrastructure-foundation/_index.md	Adds landing content and relref links to Phase 0 child pages.
content/enterprise-rollout/03-phase-1-platform-engineering/_index.md	Adds landing content and relref links to Phase 1 child pages.
content/enterprise-rollout/04-phase-2-phased-rollout/_index.md	Adds landing content and relref link to Phase 2 child page.
content/enterprise-rollout/05-phase-3-observability-and-governance/_index.md	Adds landing content and relref links to Phase 3 child pages.
content/enterprise-rollout/06-implementation-support-ecosystem/_index.md	Adds landing content and relref links to section child pages.
content/enterprise-rollout/appendix/_index.md	Adds landing content and relref links to Appendix child pages.