Update README.md

Conditional-Comments correction
Remove support for `span` syntax
Correcting conditional comment to be shorter based on PR from cbieser
Merge pull request #3 from cbieser/patch-1

Update README.md
Further conditional corrections in README
Merge remote-tracking branch 'scottjehl/refactor'

Conflicts:
	index.html
Merge pull request #133 from jansepar/master

Futher tweaks to refactor branch