fix: update form header to follow heading order

[corinneling]

We want to the heading order of the submit page to match the heading order of the about page.

To do this we can update the partial used for the header on the submit page template to match the header used in the about page template

The about page template uses the partial {{> _content__section about.content_apprentice }} on line 6 of the about page template in order to set the third heading on the about page to an h3. So we can use that same partial on the submit page. To do this change line 4 of the submit page template to be {{> _content__section submit.section_header }}

Note: some work to the heading structure is also mentioned in issue #288 but there should be no overlapping work

See screen shot of form header on the submit page:

[ProxN]

Hello I fixed this here my pull request here