cli/config: Update 'set' command description

lib/cli/commands/config.js

@@ -12,12 +12,12 @@ const configCommand = {
 configCommand.builder = function(cli) {
 	return cli
 		.demandCommand(1, "Command required. Available commands are 'set', 'get' and 'list'")
-		.command("set <key> [value]",
-			"Set the value for a given configuration key. Provide no unset the configuration", {
-				handler: handleConfig,
-				builder: noop,
-				middlewares: [baseMiddleware],
-			})
+		.command("set <key> [value]", "Set the value for a given configuration key. " +
+			"Or clear an existing configuration by omitting the value", {
+			handler: handleConfig,
+			builder: noop,
+			middlewares: [baseMiddleware],
+		})
 		.command("get <key>", "Get the value for a given configuration key", {
 			handler: handleConfig,
 			builder: noop,