Fixed some typos in the documentation

Based on user feedback, it was very non-obvious that if using an
web server other than multiplex/index.js it would be necessary to
upload the socket.io client libs. This negates that problem.

Conflicts:
	README.md
	index.html
	js/reveal.js
	package.json
	plugin/speakernotes/client.js

embed a generic search button icon.

Allow HTML tags in external markdown files