patch applied (ghc): Documentation only: update External Core section of user guide

[Tim Chevalier]

Sun Feb 17 13:32:06 PST 2008  Tim Chevalier <chevalier at alum.wellesley.edu>
  * Documentation only: update External Core section of user guide
  
  I updated the External Core section of the user guide, mostly to reflect
  that the input path is broken and there are no firm plans to fix it. 

    M ./docs/users_guide/using.xml -12 +9