Fixing the sig-contribx/README.md markdown.
Fixing the sig-contribx/README.md markdown.

I am in the 2017 KubeCon Berlin. We are talking about contribution
and that lead me to this page. I noticed the page does not render
in markdown correctly when looking at it in a browser:
https://github.com/mbruzek/community/tree/master/sig-contribx

bgrant0607/community,kubernetes/community,pwittrock/community,pwittrock/community,kubernetes/community,bgrant0607/community,kubernetes/community