POD has you covered. From perldoc perlpod:

For, begin, and end will let you have regions of text/code/data
that are not generally interpreted as normal POD text, but are
passed directly to particular formatters, or are otherwise special.
A formatter that can use that format will use the region, otherwise
it will be completely ignored.
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So you could write a Markdown POD formatter that would look for these and interpret the paragraphs as Markdown.

=begin markdown

# PARAMETERS

The following are good parameters:

* **-foo**
...

=end markdown
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Since the text is otherwise ignored if the formatter doesn't know how to handle it, you don't get weird-looking stuff in your output if this runs through the usual POD formatter.