[All] Usage scenarios doc - publication related changes

Hi all,

I made various changes to the usage scenario doc, see the attached HTML 
version and the diff:

- updated various link that have a redirect, e.g. to tinyurl
- some punctation changes
- added links, e.g. to http://validator.nu
- changed nesting of lists
- aligned the "details" sections, e.g. have always "running code"

If you have any further comments I can accommodate them by 2 p.m. CET today.

Thanks,

Felix