Use level-two heading in Related Topics example

There is a linter in place which complains about multiple top-level headings in the same page:

MD025/single-title/single-h1 Multiple top-level headings in the same document [Context: "# Related topics"]

I suppose it applies to most pages that the Related topics section is not the only top-level heading of the page, thus a level-two heading may be a better example.