Launch Essentials Doc Update

[rachelwhitton]

Re: Launch Essentials

Priority: Medium

Issue Description:

Re: https://community.pantheon.io/forum/t/feature-request-email-template-for-dns-entries/102

Suggested Resolution

Add a template in the docs to make for easier handoff of DNS change requests. Consider cross-linking to that new docs resource within the relevant product context as well

[rachelwhitton]

consider single vs few vs bulk variants