Doc Request: Document meanings of file types shown when -v is used

[Brian-at-Baebies]

During savefs operation with -v argument, output looks like:

-[00][ 55%][SYMLINK ] /var/lib/ghostscript/CMap/Adobe-Japan1-UCS2
-[00][ 55%][DIR     ] /var/lib/ghostscript/fonts
-[00][ 55%][REGFILEM] /var/lib/ghostscript/fonts/Fontmap
-[00][ 55%][REGFILEM] /var/lib/ghostscript/fonts/cidfmap
-[00][ 55%][DIR     ] /var/lib/usbutils
-[00][ 55%][REGFILE ] /var/lib/usbutils/usb.ids
-[00][ 55%][DIR     ] /var/lib/apt

Most of the types shown (third [...] field) are pretty obvious to folks with any background knowledge, but I don't know what REGFILEM is and how it differs from REGFILE. Please update the fsarchiver documentation to define all the possible terms that can appear in that field.