mhbuild.man: Avoid using format-free printf(3) in example.
mhbuild.man: Avoid using format-free printf(3) in example.

It pops up in searches for printf()s that could be fputs(),
and as printf() it doesn't output the trailing `\n' to end the line.
Replace with puts().  Lowercase Kernighan's message, as he wrote it.

mcr/nmh,mcr/nmh