[Cin] add Frame on PiP on manual

[Andrea paz]

@Phyllis
You are right, the file size could be a problem. Putting the images on
a web service (postimage; etc) and compressing the text odt file as an
attachment to the post should keep the space taken up a lot. A generic
contribution should only cover a section of a chapter in the manual,
so there should be no size problem. But better to hear Sam's opinion
as well.
As for the danger of leaving a thread open without getting to Latex,
it is true: it is a real danger.

@Georgy
I have never used Lyx but I see that it still relies on texlive. I was
just thinking about the possibility that contributors don't want to
have anything to do with Latex. LibreOffice is about not forcing users
to install and learn other programs. Maybe txt would be better, but
you can't keep track of the various contributors.