Added smart volume size explanation

modules/archive.sh

@@ -44,6 +44,7 @@ check_input() {
 	echo "Archiving file/directory '${input_file}' with password '${archive_pwd}' and size '$size'" >&2
 }
 
+# Calculates a "smart" volume size so that each volume (including the final part) will be approximately the same size
 calc_smart_volumes() {
 	total_size=$(du -s -BM "${input_file}" | grep -oP '^\d+') || return
 	num_volumes=$(echo "($total_size + $size - 1) / $size" | bc)