CLI and GDB/MI documentation patch

[Bob Rossi]

> > As for old behavior, since the old versions of protocol/MI is already
> > supported by the tools whose authors are the audience of these NEWS
> > sections, I'd expect them to be well acquainted with the old behavior.
> > So I don't think they will need to look for that.
> 
> No, I can't support that assumption.  New tools, written today, are
> probably written against a fairly current manual.  Then someone
> approaches you and says "I'd like to use your nice IDE on our stable
> enterprise platform from three years ago which has an older GDB".  The
> range of supported GDBs does not only grow forwards.

This is definatly true. I had to make CGDB work with GNAT GDB 3.14p 
cause I'm forced to use that compiler at work. That GDB is many years
old. (This was using annotate 2 however).