Add little tutorial how to use a2lixTranslationFormBundle with AdmingeneratorGeneratorBundle

I think that this little tutorial will be useful. [a2lixTranslationFormBundle ][1] is cool bundle :-) 

**p.s**  I don't  sure in my English, so maybe in my tutorial exist little errors. And I don't sure if image will be display good. This is my first tutorial on Github....

[1]: https://github.com/a2lix/TranslationFormBundle