Fix doc links [skip ci]

pinepain · pinepain · commit fc6b747a23db · 2017-10-14T23:47:02.000+03:00
diff --git a/docs/README.md b/docs/README.md
@@ -52,6 +52,6 @@ $result = $script->run($context);
 echo $result->value(), PHP_EOL;
 ```
 
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+[v8-hello-world]: https://chromium.googlesource.com/v8/v8/+/master/samples/hello-world.cc
+[v8-intro]: https://developers.google.com/v8/intro
+[php-v8-stubs]: https://github.com/pinepain/php-v8-stubs
