Add some doc comments

alpine-make-vm-image

@@ -104,6 +104,7 @@ help() {
 	exit ${1:-0}
 }
 
+# Cleans the host system. This function is executed before exiting the script.
 cleanup() {
 	set +eu
 	trap '' EXIT HUP INT TERM  # unset trap to avoid loop
@@ -250,6 +251,7 @@ umount_recursively() {
 		| xargs umount -rn
 }
 
+# Downloads the specified file using wget and checks checksum.
 wgets() (
 	local url="$1"
 	local sha256="$2"