feat: platform documentation update (#244)

Major updates to the platform documentation to enhance usability,
completeness, and clarity across developer journeys. The changes include
structural improvements, updated content, and removal of outdated
sections.

### Key Additions and Updates

1. **Homepage Redesign & Navigation**
   - Introduced a refreshed homepage layout
- Improved documentation grouping and sidebar navigation for better user
flow

2. **User Profile End-to-End Example**
- Added a comprehensive walkthrough showcasing the full developer
journey:
     - Smart contract creation
     - Subgraph and indexing setup
     - Integration with Graph Middleware
     - API portal exposure and testing

3. **Knowledge Bank Section**
New section added to house conceptual guides and development best
practices

4. **Supported Blockchains Overview**
   Introduced a dedicated section on supported networks

5. **Summary & Keyword Enhancements**
Added summaries and keyword blocks to all major pages for quick scanning
and contextual relevance

6. **Platform Image Updates**
Replaced outdated visuals with current screenshots of the platform
interface

7. **EVM & Fabric Protocol Guide Revisions**
Updated guides with latest screenshots, architecture flows, and
configuration examples

8. **Cleanup of Deprecated Content**
Removed redundant and outdated sections no longer relevant to the
current platform capabilities

Author: gyan-sharma