ANN: Updating flag description in the User's Guide

[Jan Stolarek]

> What about standardizing on an 'experimental' prefix such as -fx-use-rpaths
> or -fx-kill-oneshot? These flags would not be added to the user guide and
> their intent clear when actually using them.
As already stated in an earlier reply I think we should have documentation for the sake of other 
developers.

I don't like the idea of separate prefix for experimental flags. This could be problematic when 
the flag becomes stable - we would have to change its name and that would break backwards 
compatibility.

Janek