include "-all" parameter to dependency installer description

If I run DependencyInstaller without any input flag it throws an error, so I believe this is the right description

Signed-off-by: Augusto Berndt <[email protected]>

Author: gudeh

etc/DependencyInstaller.sh

@@ -235,7 +235,7 @@ _help() {
     cat <<EOF
 
 All arguments and flags are only applicable for OpenROAD dependencies
-Usage: $0
+Usage: $0 -all
                                 # Installs all of OpenROAD's dependencies no
                                 #     need to run -base or -common. Requires
                                 #     privileged access.