add link to xero's dotfiles, with info about managing them with gnu stow

in the linux world we take dotfiles seriously. i've started to manage mine with gnu stow, and it's been great. the [readme](https://github.com/xero/dotfiles/blob/master/README.md) in my dotfiles repo is a guide dedicated to teaching people to use stow to manage theirs (and work with mine). people must like the idea, because i have a growing number of forks and stars :grinning: 

my dotfiles have *lots* of configs and themes including: 
- awesome wm
- compton
- linux fonts
- figlet
- git
- herbstluftwm
- midnight commander
- mpd
- ncmpcpp
- pacman
- sublime text
- vim
- urxvt
- zsh