bug#22042: don't say K bytes on both head and tail's man pages

[Dan Jacobson]

On both the head and tail man pages,
can you kindly not use "K"?

       -c, --bytes=K
              output the last K bytes; or use -c +K to output  bytes  starting
              with the Kth of each file

K bytes sounds like kilobytes.

Yes if one reads carefully it doesn't.

But instead if you used X, then one needn't read carefully and could
still read the page!

Or how about B? B bytes. Sounds even better than X.

Anyway it (K) appears several places on both man pages.