Add Hashgraph Online (HOL) Standards SDK & Registry Broker Documentation

## Documentation Request: Hashgraph Online (HOL)

### What is Hashgraph Online (HOL)?

Hashgraph Online (HOL) is a **Universal Agentic Registry** - the decentralized directory for AI Agents and MCP Servers. It provides blockchain-based identity, discovery, and encrypted communication infrastructure for autonomous AI agents across Web2 and Web3.

HOL is maintained by a consortium of 10 organizations building open standards for the autonomous internet, with 28M+ HCS transactions processed and 300K+ daily API requests.

### Why Developers Need This

Developers building with HOL need quick access to documentation for:

- **AI Agent Development**: Building autonomous agents with verifiable on-chain identity (HCS-10, HCS-11, HCS-14 standards)
- **Agent Registry Integration**: Discovering, registering, and communicating with AI agents across multiple protocols (A2A, MCP, XMTP, ERC-8004)
- **MCP Server Integration**: Connecting Claude Desktop, Cursor IDE, and other MCP-compatible tools to the agentic registry
- **Encrypted Agent Communication**: Implementing server-blind encrypted messaging between agents
- **Multi-Protocol Chat**: Building chat applications that work across Agentverse, Virtuals, OpenRouter, and more

### Documentation URLs

| Resource | URL |
|----------|-----|
| **Main Documentation** | https://hol.org/docs/registry-broker/ |
| **Standards SDK Docs** | https://hol.org/docs/libraries/standards-sdk/ |
| **API Reference** | https://hol.org/docs/registry-broker/api/client |
| **HCS Standards** | https://hol.org/docs/standards |
| **Live Registry** | https://hol.org/registry |

### GitHub Repository

- **Standards SDK**: https://github.com/hashgraph-online/standards-sdk
- 45+ stars, Apache-2.0 license
- TypeScript SDK with comprehensive documentation
- Active development (343+ commits)

### npm Packages

```bash
npm install @hashgraphonline/standards-sdk
npm install @hol-org/standards-sdk
npm install @hol-org/rb-client
```

### Documentation Quality

✅ Well-structured Docusaurus-based documentation
✅ Comprehensive API reference with code examples
✅ Getting started guides and tutorials
✅ Active maintenance by the Hashgraph Online DAO
✅ Multiple SDKs and libraries documented
✅ Standards specifications (21+ HCS standards)

### Key Documentation Sections

1. **Registry Broker** - Agent discovery, registration, and chat relay
2. **Standards SDK** - Core SDK implementing HCS standards
3. **MCP Server** - Model Context Protocol integration
4. **Encrypted Chat** - Server-blind encrypted communications
5. **ERC-8004** - On-chain agent verification (Ethereum, Solana)
6. **XMTP Integration** - Decentralized messaging

### Use Cases

- Building AI agents with blockchain identity
- Creating MCP servers for Claude/Cursor integration
- Implementing agent-to-agent communication
- Developing decentralized AI applications
- Building on Hedera Hashgraph

Thank you for considering this addition!