Manpages of freetype2-demos in Debian buster

• ftbench(1)
• ftdiff(1)
• ftdump(1)
• ftgamma(1)
• ftgrid(1)
• ftlint(1)
• ftmulti(1)
• ftstring(1)
• ftvalid(1)
• ftview(1)
• ttdebug(1)