Re: 1.3 docs/installation.txt updates

> Below is an edit to installation.txt that I hope addresses the
> problems I had. I intentionally left some paragraphs badly
> formatted (line length) so that a diff would be easier to
> read. !}fmt will fix them. Yell, and I'll do that.
> 
> I intentionally left the overall format otherwise untouched.
> 
> Summary of changes:
> * Some missing/duplicated info between RPM and tarball installs;
> untangled.
> 
> * Steps in encryption.txt not needed, so dereferenced. 
> 
> * stunnel.pem: references to, but not created; made clear is same
> as current.pem.
> 
> * Client must run rhn_register even after editing client config.

  I think it could be stated here that you can use whatever values while
running rhn_register with current. Server simply ignores them.

  And also I think it would be nice to mention that one should mirror
updates tree oneself with something like mirror script.
http://freshmeat.net/redir//6458/url_homepage/mirror.
  wget if fine too just wget does not delete old files.

  And rerun cadmin create <channel> after such update.

  Mindaugas