docs: clarify staging vs production dashboard URLs

Note that app.staging.ampersend.ai is for testnet and
app.ampersend.ai is for production/mainnet.

Author: pcarranzav

python/examples/docs/running-mcp-proxy.md

@@ -39,7 +39,7 @@ pnpm build
 
 ### 2. Configure Wallet
 
-**Recommended: Smart Account** (from app.staging.ampersend.ai)
+**Recommended: Smart Account** (from app.staging.ampersend.ai for testnet, app.ampersend.ai for production)
 
 ```bash
 export BUYER_SMART_ACCOUNT_ADDRESS=0x...           # From staging dashboard