new strings for upsell banner tooltip

en/banner.ftl

@@ -136,7 +136,9 @@ modal-email-domain-success-continue = Continue
 
 tooltip-email-domain-explanation-title = About your unique { -brand-name-relay } Email Domain
 tooltip-email-domain-explanation-part-one = This valuable feature of your { -brand-name-relay-premium } account lets you choose a unique { -brand-name-relay } email domain that you can use to create unlimited, custom { -brand-name-relay } masks on the go.  
-tooltip-email-domain-explanation-part-two = There’s no need to sign into { -brand-name-relay } to generate a new mask; Simply add any word or phrase before the @ symbol of your { -brand-name-relay } email domain to instantly create a new mask anywhere you are. 
+tooltip-email-domain-explanation-part-two = There’s no need to sign into { -brand-name-relay } to generate a new mask; Simply add any word or phrase before the @ symbol of your { -brand-name-relay } email domain to instantly create a new mask anywhere you are.
+tooltip-email-domain-explanation-title-free = Get your own { -brand-name-relay } Email Domain
+tooltip-email-domain-explanation-part-one-free = With { -brand-name-premium }, you can create unlimited, custom { -brand-name-relay } masks on the go using a unique { -brand-name-relay } email domain — you won’t even have to generate them here first.
 # Variables:
 #   $mozmail (string): domain used by Relay masks (mozmail.com)
 # "yourdomain" is used as an example custom domain. Keep it lowercase without space and in latin characters, to resemble and actual email address. Example: [email protected]