Add note about Solarized color theme

themes/guru.zsh-theme

 #-------------------------------------------------------------------------------
 # Guru theme for oh-my-zsh by Adam Lindberg (eproxus@gmail.com)
+# Intended to be used with Solarized: http://ethanschoonover.com/solarized
 # (Needs Git plugin for current_branch method)
 #-------------------------------------------------------------------------------
 
-
 # Color shortcuts
 R=$fg[red]
 G=$fg[green]