Fix dnssec-policy options formatting and links in ARM

Fix dnssec-policy options formatting and links in ARM

The statements that already exist in the grammar can't be created with
the namedconf:statement. Use a plain definition list for these
statements and add a manual anchor for each one so links to them can be
created.

Avoid using the :any: syntax in the definition lists, as that just
creates a link to the duplicate and completely unrelated statement,
which just makes the documentation more confusing.