Content: Update references to DNS hosting to align with our new service

[montecristo99]

Issue description

In multiple places on get.gov and in our email communications, we mention that we do not offer DNS hosting. We need to update these references to reflect the fact that we will now be offering this service.

Acceptance criteria

• Update the bottom of the About page, where we say we do not offer DNS hosting. Relevant Google doc is here.
• Update Before you request a .gov domain, where we say we do not offer DNS hosting. (Google doc is here.)
• Review and revise any email communications that currently say we do not offer DNS hosting.
  • .gov Emails (domain info) --> Pre-ready
  • .gov Emails (domain requests) --> Approved
• Share these updates with product and the DNS hosting pod.
• Create another issue in this parent issue to implement this work (or confirm w/Product that another issue isn't needed)

Additional context

This is the internal content creation work, not the preparation of that content for publication on get.gov! The final A/C will get us there, though.

Links to other issues

• 🔄 Create information page and step-by-step help content for DNS hosting #495