Add the condition of at least 3 months to referral program

app/dashboard/templates/dashboard/referral.html

@@ -17,7 +17,7 @@
 
     <div class="alert alert-primary collapse" id="howtouse" role="alert">
       On this page, you can create a <b>referral code</b> that you can use when referring people to SimpleLogin.
-      For every user who <b>upgrades</b>, you'll get $5 :). <br>
+      For every user who <b>upgrades</b> and stays with us at least 3 months, you'll get $5 :). <br>
       The payout can be initiated any time, just send us an email at
       <a href="mailto:hi@simplelogin.io">hi@simplelogin.io</a> when you want to receive the payout.
     </div>