Clarify help information for --global

shell-completion/zsh/_systemctl.in

@@ -485,7 +485,7 @@ _arguments -s \
     '--system[Connect to system manager]' \
     '--user[Connect to user service manager]' \
     "--no-wall[Don't send wall message before halt/power-off/reboot]" \
-    '--global[Enable/disable/mask unit files globally]' \
+    '--global[Enable/disable/mask default user unit files globally]' \
     "--no-reload[When enabling/disabling unit files, don't reload daemon configuration]" \
     '--no-ask-password[Do not ask for system passwords]' \
     '--kill-who=[Who to send signal to]:killwho:(main control all)' \

src/systemctl/systemctl.c

@@ -277,7 +277,7 @@ static int systemctl_help(void) {
                "     --legend=BOOL       Enable/disable the legend (column headers and hints)\n"
                "     --no-pager          Do not pipe output into a pager\n"
                "     --no-ask-password   Do not ask for system passwords\n"
-               "     --global            Enable/disable/mask unit files globally\n"
+               "     --global            Enable/disable/mask default user unit files globally\n"
                "     --runtime           Enable/disable/mask unit files temporarily until next\n"
                "                         reboot\n"
                "  -f --force             When enabling unit files, override existing symlinks\n"