docs: fix code snippet in README (#878)

Author: neerajgupta2407

README.md

@@ -95,10 +95,10 @@ from sendgrid.helpers.mail import *
 
 sg = sendgrid.SendGridAPIClient(api_key=os.environ.get('SENDGRID_API_KEY'))
 from_email = Email("test@example.com")
-to_email = Email("test@example.com")
+to_email = To("test@example.com")
 subject = "Sending with SendGrid is Fun"
 content = Content("text/plain", "and easy to do anywhere, even with Python")
-mail = Mail(from_email, subject, to_email, content)
+mail = Mail(from_email, to_email, subject, content)
 response = sg.client.mail.send.post(request_body=mail.get())
 print(response.status_code)
 print(response.body)