Fixed command to check perl module version

README.md

@@ -16,7 +16,7 @@ RECOMMENDED: strawberry perl environment [strawberry-perl-5.30.3.1-64bit-portabl
 * Perl version 5.28 or higher
 * cpan or cpanm
 * several CPAN modules such as Archive::BagIt (0.065 or higher)
-  * `cpan -d Archive::BagIt` to check module perl version
+  * `sudo cpan -D Archive::BagIt` to check module perl version
 
 ## Three ways to install a module
 * with cpan `cpan Archive::BagIt`