docs(api): add Trading API integration guide

docs/api/overview.md

@@ -10,6 +10,15 @@ Welcome to the Uniswap API documentation. Uniswap provides several APIs and data
 
 ## Available APIs
 
+### Trading API
+The Uniswap Trading API provides quote generation and transaction building for token swaps across 25+ chains.
+
+- **[Trading API Overview](./trading/overview)** - Get started with the Trading API
+- **[Integration Guide](./trading/integration-guide)** - Complete implementation guide with schemas and best practices
+- **Quote & Swap Endpoints** - Generate quotes and build unsigned transactions
+- **Permit2 Support** - Gasless approvals via EIP-712 signatures
+- **Cross-Chain Swaps** - Multi-step cross-chain swap support
+
 ### Subgraph API
 The Uniswap Subgraph provides a GraphQL API for querying historical and real-time data from the Uniswap protocol.
 
@@ -35,6 +44,7 @@ Get real-time and historical price data for tokens on Uniswap.
 
 ### For Developers
 If you're building applications that need to:
+- Execute token swaps → Use the **[Trading API](./trading/overview)**
 - Query historical trading data → Use the **Subgraph API**
 - Get optimal swap routes → Use the **Routing API**
 - Display token prices → Use the **Price APIs**

docs/api/subgraph/_category_.json

@@ -1,5 +1,5 @@
 {
   "label": "Subgraph",
-  "position": 2,
+  "position": 3,
   "collapsed": false
 }

docs/api/trading/_category_.json

@@ -0,0 +1,5 @@
+{
+  "label": "Trading API",
+  "position": 2,
+  "collapsed": false
+}