Fixed manpages

Manpages were including the text .5v at the end of some paragraphs. This was
caused by an old hack in the Makefile which removed the text .sp, which was
accidently added to the end of some paragraphs. (sed -i 's/\.sp//') Looks like
this hack is not needed any longer so it was just commented out and so the .5v
disappeared (which might have been the text ".sp 5v")
Minor change in manpage
Replaced all occurences of grml with Grml in the manpages
Replaced all occurences of iso or Iso with ISO(s) in the manpages
Merge branch 'master' of https://github.com/jimmy42/grml2usb
docs: fix typo (persisten*t*-path and wrong uppercase usage of Grml64/Grml in syslinux)