Updated def build_personalization

Corrected a typo.

Author: theanuraganand

examples/helpers/mail/mail_example.py

@@ -30,7 +30,7 @@ def build_personalization(personalization):
         mock_personalization.add_to(cc_addr)
 
     for bcc_addr in personalization['bcc_list']:
-        mock_personalization.add_bc(bcc_addr)
+        mock_personalization.add_bcc(bcc_addr)
 
     for header in personalization['headers']:
         mock_personalization.add_header(header)
@@ -216,4 +216,4 @@ def send_kitchen_sink():
 send_hello_email()
 
 # this will only send an email if you set SandBox Mode to False
-send_kitchen_sink()
+send_kitchen_sink()