Added service example to README, see #529 [ci skip]

README.md

@@ -165,6 +165,44 @@ var message = new AwesomeMessage({ awesomeField: "AwesomeString" });
 
 Custom classes are automatically populated with static `encode`, `encodeDelimited`, `decode`, `decodeDelimited` and `verify` methods and reference their reflected type via the `$type` property. Note that there are no methods (just `$type`) on instances by default as method names might conflict with field names.
 
+### Using services
+
+```protobuf
+// greeter.proto
+service Greeter {
+    rpc SayHello (HelloRequest) returns (HelloReply) {}
+}
+
+message HelloRequest {
+    string name = 1;
+}
+
+message HelloReply {
+    string message = 1;
+}
+```
+
+```js
+...
+var Greeter = root.lookup("Greeter");
+var greeter = Greeter.create(rpcImpl);
+
+greeter.sayHello({ name: 'you' }, function(err, response) {
+    console.log('Greeting:', response.message);
+});
+```
+
+To make this work, all you have to do is provide an `rpcImpl`, which is is an asynchronous function that takes the reflected service method, the binary HelloRequest and a node-style callback as its parameters. For example:
+
+```js
+function rpcImpl(method, requestData, callback) {
+    // perform the request using an HTTP request or a WebSocket for example
+    var responseData = ...;
+    // and call the callback with the binary response afterwards:
+    callback(null, responseData);
+}
+```
+
 ### Usage with TypeScript
 
 ```ts

src/util.js

@@ -98,7 +98,11 @@ util.asPromise = asPromise;
 function fetch(path, callback) {
     if (!callback)
         return asPromise(fetch, util, path);
-    try { return eval(['req','uire'].join(''))("fs").readFile(path, "utf8", callback); } catch (e) { } // eslint-disable-line no-empty, no-eval
+    try {
+        // Hide this from webpack. There is probably another, better way.
+        return eval(['req','uire'].join(''))("fs") // eslint-disable-line no-eval
+              .readFile(path, "utf8", callback);
+    } catch (e) { } // eslint-disable-line no-empty
     var xhr = new XMLHttpRequest();
     function onload() {
         if (xhr.status !== 0 && xhr.status !== 200)