Make headers in KDoc smaller

Now at least some of kdocs use h2 header. It's way too big compared to other text. I suggest to make it h4 / use bold

Start by locating the KDoc sources or documentation-generation configuration that produces the oversized h2 headers. Compare the generated KDoc headings with surrounding text, then adjust the heading styling or level so these headers render as h4 or bold. Verify the generated documentation shows the smaller treatment consistently.

Written by the indexing model from the issue text.