refactor(docs): add collapsible categories to Learn section examples

[Nancy-Chauhan]

Description

Restructured the Learn section examples to improve learning progression and developer experience by reordering examples from beginner to advanced complexity, and reorganizing "More Examples" categories with clearer internal progression.

Type of Change

• Content improvement
• Bug fix (errors, broken links, outdated info)
• New content
• Other: ____

Related Issues/PRs (if applicable)

• Closes #____
• Related SDK PR: agno-agi/agno#____

Checklist

• Content is accurate and up-to-date
• All links tested and working
• Code examples verified (if applicable)
• Spelling and grammar checked
• Screenshots updated (if applicable)

Files Changed

• docs.json - Updated Learn tab navigation with nested collapsible groups

Before/After Structure

Before:

Agent Examples (27 flat list)
Team Examples (8 flat list)
Workflow Examples (6 flat list)

After:

Agent Examples
  ├── 5 featured examples
  └── More Agent Examples (accordion)
      ├── Content & Media (5)
      ├── Research & Knowledge (3)
      ├── Business & Analysis (4)
      ├── Personal Assistants (5)
      ├── MCP Integration (1)
      └── Tools & Utilities (2)

Team Examples
  ├── 5 featured examples
  └── More Team Examples (accordion)
      └── 3 additional teams

Workflow Examples (all 6 visible)