Update transactional-templates.md

[kylearoberts]

There is no need for <%body%> in the email template as it does not work in dynamic templates. Also, the email send does not need a subject, text, or HTML section as those are all set in the template.

[SendGridDX]

All committers have signed the CLA.

[thinkingserious]

Hello @kylearoberts,

Thanks again for the PR!

It's HACKTOBERFEST! We want to show our appreciation by sending you some special Hacktoberfest swag. If you have not already, could you please fill out this form so we can send it to you? Thanks!

Team SendGrid DX

[thinkingserious]

Hello @kylearoberts,

Thanks again for the PR!

You have earned 31 out of the 5 points needed to receive glorious SendGrid Hacktoberfest swag.

Please take a moment to checkout this link to find more issues to get you past the required threshold or to simply continue the celebration.

Also, please be sure you have officially registered with us here by November 1, 2018 to qualify.

If you have any questions you can email us at dx+hacktoberfest2018@sendgrid.com.

Thank you and Happy Hacktobering!

Team SendGrid