DOCS-1257 - Move free trial button from header

[jpipkin1]

Purpose of this pull request

This pull request moves the "Start free trial" button from the header.

Select the type of change

• Minor Changes - Typos, formatting, slight revisions
• Update Content - Revisions, updating sections
• New Content - New features, sections, pages, tutorials
• Site and Tools - .clabot, version updates, maintenance, dependencies, new packages for the site (Docusaurus, Gatsby, React, etc.)

Ticket (if applicable)

DOCS-1257

[jpipkin1]

@kimsauce, could you look at this draft? It merely removes the Start free trial button from the header and adds one to the main page. But the button in the main page does not track clicks like the old one did.

[kimsauce]

thanks for doing this