binfmt_misc: touch up documentation a bit

Line wrap the content to 80 cols, and add more details to various fields
to match the code.  Drop reference to a website that does not exist
anymore.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>