add faq.en.md

[Jianbo-Ning]

translate faq.md into faq.en.md

[tencent-adm]

Thank you for your submission, we really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[nihui]

Thanks for your contribution !