Update doc for NodePackageImporter

lib/sass/node_package_importer.rb

@@ -4,6 +4,8 @@ module Sass
   # The built-in Node.js package importer. This loads pkg: URLs from node_modules
   # according to the standard Node.js resolution algorithm.
   #
+  # @param entry_point_directory [String] The directory where the {NodePackageImporter} should start when resolving
+  #   `pkg:` URLs in sources other than files on disk.
   # @see https://sass-lang.com/documentation/js-api/classes/nodepackageimporter/
   class NodePackageImporter
     def initialize(entry_point_directory)