Providing some KDevelop documentation

[Wolfgang Bangerth]

> Ah yeah, while we're at it, it would also be great if we would have
> some documentation about working-sets. :-)
> 
> Here's the related blog post:
> http://zwabel.wordpress.com/2009/06/21/kdevelop4-ui-areas-working-sets-etc/

Ah, I think I finally understand how they work :-)

I had copied a bit of text as you noticed from the documentation that was 
there, but it wasn't quite clear to me what you could actually do with working 
sets apart from close all tabs at once. I'll add a brief description of 
working sets and what you can do with them.

Best
 W.

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Wolfgang Bangerth                email:            bangerth at math.tamu.edu
                                 www: http://www.math.tamu.edu/~bangerth/