RFA: update MI breakpoint documentation

[Tom Tromey]

>>>>> "Yao" == Yao Qi <yao@codesourcery.com> writes:

>> +@item printf
>> +FIXME

Yao> I suggest that we leave this FIXME here.

Yao> My pending patch <[PATCH 2/3] Remove dead code for dprintf,
Yao> http://sourceware.org/ml/gdb-patches/2012-12/msg00376.html> is to
Yao> remove field 'printf'.  I can update the doc here when the patch is
Yao> approved.

I think I might as well just delete it now.

Tom