Doc: Add link to a new tutorial

Author: GitauHarrison

README.md

@@ -46,6 +46,7 @@ This repository holds all the notes of the things I have learnt. Anyone else can
 39. [Joined Table Inheritance](databases/99_joined_table_inheritance.md)
 40. [Object-Oriented Programming in Python](oop_python.md)
 41. [Email Support in Flask](email_support_in_flask.md)
+42. [Email verification using SendGrid, Verify and Flask](/twilio_sendgrid/04_email_verification.md)
 
 ## Django Articles