Update README.md

Author: MailboxValidator

README.md

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+[![Latest Stable Version](https://img.shields.io/gem/v/mailboxvalidator_ruby.svg)](https://rubygems.org/gems/mailboxvalidator_ruby)
+[![Total Downloads](https://img.shields.io/gem/dt/mailboxvalidator_ruby.svg)](https://rubygems.org/gems/mailboxvalidator_ruby)
+
 MailboxValidator Ruby Module
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