Improve documentation

Author: yadaiio

README.md

@@ -34,15 +34,21 @@ as defined in [RFC 6763](https://tools.ietf.org/html/rfc6763).
 Once [installed](#install), you can use the following code to look up the address of a local domain name:
 
 ```php
+<?php
+
+require __DIR__ . '/vendor/autoload.php';
+
 $factory = new Factory();
 $resolver = $factory->createResolver();
 
 $resolver->lookup('hostname.local')->then(function ($ip) {
    echo 'Found: ' . $ip . PHP_EOL;
+}, function (Exception $e) {
+    echo 'Error: ' . $e->getMessage() . PHP_EOL;
 });
 ```
 
-See also the [examples](examples).
+See also the [examples](examples/).
 
 ## Usage
 
@@ -83,6 +89,10 @@ Sending queries uses a [Promise](https://github.com/reactphp/promise)-based inte
 (i.e. either successfully resolved or rejected with an error):
 
 ```php
+<?php
+
+require __DIR__ . '/vendor/autoload.php';
+
 $resolver->lookup($hostname)->then(
     function ($ip) {
         // IP successfully resolved
@@ -105,6 +115,10 @@ you should look into also using [clue/reactphp-block](https://github.com/clue/re
 The resulting blocking code could look something like this:
 
 ```php
+<?php
+
+require __DIR__ . '/vendor/autoload.php';
+
 use Clue\React\Block;
 
 $factory = new Factory();
@@ -123,6 +137,10 @@ try {
 Similarly, you can also process multiple lookups concurrently and await an array of results:
 
 ```php
+<?php
+
+require __DIR__ . '/vendor/autoload.php';
+
 $promises = array(
     $resolver->lookup('first.local'),
     $resolver->lookup('second.local'),