do not use angle brackets in hyperlink labels

Hello,

I'm very happy with Hugo which made me into learning Go, but being a noob can't contribute code. :-(

However, I noticed in the docs that markdown implementation in Go has problems rendering hyperlabels which use angle brackets around URLs- check: http://hugo.spf13.com/templates/go-templates

So, here is small patch which fixes those hyperlinks.

Sincerely,
Gour