[demo-list] Added Mixbolt to the demo list (#4)

You can merge this Pull Request by running:

  git pull https://github.com/adaline/demo-list master

Or you can view, comment on it, or merge it online at:

  https://github.com/WebAudio/demo-list/pull/4

-- Commit Summary --

  * Added Mixbolt to the demo list

-- File Changes --

    M README.md (9)

-- Patch Links --

https://github.com/WebAudio/demo-list/pull/4.patch
https://github.com/WebAudio/demo-list/pull/4.diff