more readable removal of mailto: prefix

Author: DanielYang59

lib/proto/mailto.js

@@ -6,7 +6,7 @@ module.exports.check = (link, opts, callback) => {
     import('node-email-verifier').then((mod) => {
         const emailValidator = mod.default;
         const address = link
-            .substr(7)      // strip "mailto:"
+            .replace(/^mailto:/i, '')
             .split('?')[0]; // trim ?subject=blah hfields
 
         /* per RFC6068, the '?' is a reserved delimiter and email addresses containing '?' must be encoded,