patch #6927: Documentation patches
* doc/avrdude.texi: Fix various typos, and remove the last
remnants of obsoleted options -i/-o/-m/-f.
* avrdude.1: Merge typo fixes from avrdude.texi where
applicable.
git-svn-id: svn://svn.savannah.nongnu.org/avrdude/trunk@914 81a1dc3b-b13d-400b-aceb-764788c761c2