Update sample so it works when copied & pasted into an empty file

Signed-off-by: Matthew Whitehead <[email protected]>

Author: matthew1001

CONTRIBUTING.md

@@ -4,5 +4,5 @@ We welcome contributions to the FireFly Project in many forms, and
 there's always plenty to do!
 
 Please visit the
-[contributors guide](https://hyperledger.github.io/firefly/contributors/contributors.html) in the
+[contributors guide](https://hyperledger.github.io/firefly/contributors/index.html) in the
 docs to learn how to make contributions to this exciting project.

README.md

@@ -18,12 +18,24 @@ npm install @hyperledger/firefly-sdk
 ```typescript
 import FireFly from '@hyperledger/firefly-sdk';
 
-const firefly = new FireFly({ host: 'http://localhost:5000' });
-await firefly.sendBroadcast({
-  data: [{ value: 'test-message' }],
-});
+async function main() {
+  const firefly = new FireFly({ host: 'http://localhost:5000' });
+  await firefly.sendBroadcast({
+    data: [
+      {
+        value: 'test-message',
+      },
+    ],
+  });
+}
+
+if (require.main === module) {
+  main().catch((err) => console.error(`Error: ${err}`));
+}
 ```
 
+(This example was taken from the [examples](examples) folder where you will find some other basic samples)
+
 ## Generated schemas
 
 The types for FireFly requests and responses are generated from the OpenAPI schema for FireFly. If you have