Markup for the Acknowledgement section

Hi folks,

I added more names which showed up in the GitHub issues to the Acknowledgement section [1] today, but the previous markup structure(ol list) looks too long for this document, so I have to update it as <p>. It was not so nice or tidy as it used to be. Let me know if you don’t like this change and I’m willing to reset it. 

Thanks for the good work!

—
xiaoqian

[1] http://w3c.github.io/clreq/#acknowledgement <http://w3c.github.io/clreq/#acknowledgement>