Replace child main in faq by div section

[MikeMcC399]

This PR resolves issue #3264 "Nested main element in faq".

The child main element is converted to a div element. At the same time, a stray </div> end tag is cleaned up.

Since the indenting was not correct and therefore hard to read, I added a second commit with a combination of automatic and manual reformatting.

View commit 20abd0b to look at the changes which are not caused by reformatting.

Verification

Run https://validator.w3.org/ on https://www.coronawarn.app/en/faq/ and the following error messages should no longer appear:

• "The main element must not appear as a descendant of the main element."
• "A document must not include more than one visible main element"
• "Stray end tag div."

[brianebeling]

Tested locally, no observable errors and validation runs fine. Thanks!