Update older files in the archive and add files that are new to the archive.
7z u archive.zip *.doc
updates *.doc files to archive archive.zip.
-i (Include), -m (Method), -p (Set Password), -r (Recurse), -t (Type of archive), -u (Update), -w (Working Dir), -x (Exclude),
Commands: a (Add), d (Delete),
Switches: -u (Update)