base-files: Add wifi config to wifi command usage

Since commit 5f8f8a3661 wifi detect does
not longer work and wifi config it's used to configure not yet
configured wireless devices.

This commit changes command usage to reflect that change.

Signed-off-by: David Pinilla Caparrós <dpinitux@gmail.com>

package/base-files/files/sbin/wifi

@@ -6,8 +6,8 @@
 
 usage() {
 	cat <<EOF
-Usage: $0 [down|detect|reload|status]
-enables (default), disables or detects a wifi configuration.
+Usage: $0 [config|down|reload|status]
+enables (default), disables or configures devices not yet configured.
 EOF
 	exit 1
 }