Replaced malfunctioning web.config example

I followed the instructions on http://book.cakephp.org/2.0/en/installation/advanced-installation.html#url-rewrites-on-iis7-windows-hosts and even tried some other proposed solutions found on Google which all didn't work.
Then I was pointed to this lighthouse ticket http://cakephp.lighthouseapp.com/projects/43067/tickets/113-creating-webconfig-file-in-windows-for-ii7#ticket-113-5 where user Lee Chenhwa pointed out that he got it working with the solution proposed in the Stack Overflow question http://stackoverflow.com/questions/12497904/htaccess-and-cakephp-2-on-windows-iis7 created by the ticket creator. This working solution is an improved (read more flexible solution of the also solution http://www2.palomar.edu/pages/sphillips/cakephp-with-iis-7-rewrite-rules-in-a-sub-folder/ which was found in the mean time by the ticket creator.
I tested this solution on my Windows 2008 R2 with IIS 7.5 and it works. Even renamed my cakephp installation (which confirms the improved flexibility).
Gave the rewrite installation steps some love

Linked some useful ressources, improved wording
Merge pull request #474 from ravage84/patch-5

Improved/fixed IIS rewrite installation steps