Docs rb plugin linenos option malforms output

Created by: davebowker

Hey,

I'm playing around with Jekyll a bit and I'm using your highlight_alt.rb code in the docs folder to render an example. I've found that if you add the option linenos on the tag it doesn't close the </code></pre> properly.

Simple to test, use your plugin to render some code and add linenos option.

I tried to fix it on my install but I'm not so hot with regex.

Cheers, Dave