Update README: Base as primary chain, add XRPL support docs

Author: 1bcMax

README.md

@@ -1,15 +1,18 @@
 # BlockRun LLM SDK
 
-Pay-per-request access to GPT-5.2, Claude 4, Gemini 2.5, Grok, and more via x402 micropayments on Base.
+Pay-per-request access to GPT-5.2, Claude 4, Gemini 2.5, Grok, and more via x402 micropayments.
 
 **BlockRun assumes Claude Code as the agent runtime.**
 
-**Networks:**
-- **Mainnet:** Base (Chain ID: 8453) - Production with real USDC
-- **Testnet:** Base Sepolia (Chain ID: 84532) - Developer testing with testnet USDC
+## Supported Chains
 
-**Payment:** USDC
-**Protocol:** x402 v2 (CDP Facilitator)
+| Chain | Network | Payment | Status |
+|-------|---------|---------|--------|
+| **Base** | Base Mainnet (Chain ID: 8453) | USDC | ✅ Primary |
+| **Base Testnet** | Base Sepolia (Chain ID: 84532) | Testnet USDC | ✅ Development |
+| **XRPL** | XRP Ledger Mainnet | RLUSD | ✅ New |
+
+**Protocol:** x402 v2
 
 ## Installation
 
@@ -267,6 +270,49 @@ client = LLMClient(api_url="https://testnet.blockrun.ai/api")
 response = client.chat("openai/gpt-oss-20b", "Hello!")
 ```
 
+## XRPL Chain (RLUSD Payments)
+
+BlockRun now supports payments with RLUSD on the XRP Ledger. Same models, same API - just a different payment rail.
+
+```python
+from blockrun_llm import xrpl_client
+
+# Create XRPL client (pays with RLUSD)
+client = xrpl_client()  # Uses BLOCKRUN_WALLET_KEY
+
+# Chat with any model
+response = client.chat("openai/gpt-4o", "Hello!")
+print(response)
+
+# Check RLUSD balance
+balance = client.get_balance()
+print(f"RLUSD: ${balance:.4f}")
+```
+
+### Async XRPL Usage
+
+```python
+import asyncio
+from blockrun_llm import async_xrpl_client
+
+async def main():
+    async with async_xrpl_client() as client:
+        response = await client.chat("openai/gpt-4o", "Hello!")
+        print(response)
+
+asyncio.run(main())
+```
+
+### Manual XRPL Configuration
+
+```python
+from blockrun_llm import LLMClient
+
+# Or configure manually
+client = LLMClient(api_url="https://xrpl.blockrun.ai/api")
+response = client.chat("openai/gpt-4o", "Hello!")
+```
+
 ## Environment Variables
 
 | Variable | Description | Required |