feat(#195): add contract client for REST endpoints

examples/rest-contract-private.ts

@@ -0,0 +1,24 @@
+import { ContractClient } from '../src/index';
+
+// or
+// import { ContractClient } from 'bybit-api';
+
+const key = process.env.API_KEY_COM;
+const secret = process.env.API_SECRET_COM;
+
+const client = new ContractClient({
+  key,
+  secret,
+  strict_param_validation: true,
+});
+
+(async () => {
+  try {
+    const getPositions = await client.getPositions({
+      settleCoin: 'USDT',
+    });
+    console.log('getPositions:', getPositions);
+  } catch (e) {
+    console.error('request failed: ', e);
+  }
+})();