have =make cleanall= remove .texi files in doc/

[Greg Minshall]

hi.  neither =make clean= nor =make cleanall= remove the two .texi files
built (by, e.g., =make info=) in the doc subdirectory.  this patch
removes those files with =make cleanall=.  i wasn't sure which to use,
but it sort of looked like =cleanall= might be the place.

i also noticed that =make cleanall= invokes =find= on =./contrib=, which
no longer (i assume) exists so =find= complains (which is logged, but
then ignored, by =make=).  i'm happy to do a patch for that (though it
would be, presumably, as trivial as this one).

cheers, Greg

0001-doc-Makefile-cleanall-target-now-deletes-doc-org-org.patch
Description: cleanall .texi files