Pontoon: Update Mixtepec Mixtec (mix) localization of Firefox Monitor Website

Localization authors:
- Bald3mar <baldemarls@gmail.com>

locales/mix/email-strings.ftl

@@ -0,0 +1,6 @@
+# Firefox is a brand name and should not be translated.
+-brand-name = Firefox
+# A Firefox Monitor Report is an emailed statement from Firefox Monitor containing a list of known data breaches where the user’s email address was found amongst the stolen data.
+firefox-monitor-report = Tutu ña { -product-name }
+# Button text
+verify-email-cta = Kunchee Korreo