Simplify playbooks index page by removing redundant sections

[kovtcharov]

Problem

The playbooks index page (docs/playbooks/index.mdx) contains several sections that are redundant or don't add value for users trying to find and use a playbook.

Sections to Remove

1. "How to Use Playbooks" (lines 248-270)

Generic instructions like "choose your playbook" and "follow the journey" are self-evident. Users don't need a 5-step guide to use a tutorial.

2. "Playbook Structure" (lines 274-308)

Eight accordion items describing what each playbook contains (Why Build This, Quick Start, Architecture, etc.). Users discover this naturally as they work through playbooks. This adds visual clutter without helping users.

3. "Playbook Principles" (lines 348-376)

Six cards explaining philosophy (Fast Start, Teachable, Extensible, etc.). This is marketing content that doesn't help users accomplish anything.

4. Source Code Info box (lines 7-9)

Lists source files for all playbooks, but each individual playbook already links to its own source code. Redundant at the index level.

Sections to Consider Simplifying

"Learning Path" (lines 326-344)

• Duplicates information already in the Available Playbooks section
• Links to "Coming Soon" pages that don't exist yet
• Could be removed entirely or reduced to a single sentence recommending Document Q&A as a starting point

Expected Outcome

A cleaner index page that focuses on helping users find the right playbook quickly. The Available Playbooks section with its cards is sufficient—users can scan titles and descriptions to choose.