Add staking contract integration doc (#334)

Add staking rewards contract address of Symbiotic FP and sample code for interface integration

Author: hsutaiyu

docs/staking/contract-integration.md

@@ -0,0 +1,39 @@
+# Contract Integration Notes
+
+## 1. Reward Contract
+
+**Address**: `0x04c74e8a11c669acfb7ee01012bbf5cf1e57a10d`
+
+---
+
+## 2. Interface
+
+### 2.1 `claimedAmount`
+
+Query the reward amount already claimed by a specific owner.
+
+**Code Example:**
+
+```ts
+import {keccak256, toUtf8Bytes} from 'ethers';
+
+// User wallet address (example)
+const ADDRESS = '0xabc...';
+
+// 1) Protocol type identifier
+const protocolTypeIdentifier = keccak256(toUtf8Bytes('symbiotic'));
+
+// 2) Digest used in contract call
+// For Operators
+const operatorAddressDigest = keccak256(
+    toUtf8Bytes(protocolTypeIdentifier + ADDRESS.toLowerCase()) + 'operator',
+);
+
+// For Delegators
+const ownerAddressDigest = keccak256(
+    toUtf8Bytes(protocolTypeIdentifier + ADDRESS.toLowerCase())
+);
+
+// Contract call
+// rewardsContract.claimedAmount(ownerAddressDigest);
+```

sidebars.js

@@ -88,6 +88,11 @@ module.exports = {
                             label: "Become an Operator",
                             id: "staking/become-symbiotic-fp",
                         },
+                        {
+                            type: "doc",
+                            label: "Contract Integration",
+                            id: "staking/contract-integration",
+                        },
                         {
                             type: "doc",
                             label: "FAQs",