Issues with angle-bracket URLs and other link representation

Hi! 👋

I'm using mandown for one of my projects, to render section 5 and 7 man pages.

The following working example (also attached as file below) outlines my issue with angle-bracket URLs and other link representation. (The rendered man page is created using mandown v1.0.0 and the HTML file using md4c 0.5.2).

# NAME

example - an example with links.

# DESCRIPTION

We are trying to collect all links in a **NOTES** section by adding manual footnote numbers for specific numbered list items.
However, the behavior of mandown is unexpected in several cases:

When using **URL strings**[1] without angle brackets

- they can be successfully referenced in the **NOTES** section
- but software without angle-bracket support (like `mdbook`) won't detect them and won't create clickable links for them.

When using **angle-bracket URLS**[2] in the **NOTES** section

- `mandown` creates an auto-numbered footnote for the link right under it in the **NOTES** section, with formatting that we can't influence,
- angle-bracket aware software (like `mdbook`) can render HTML with clickable link in the **NOTES** section

When using **[reference-style links]** inline, they exhibit similar behavior to **angle-bracket URLS**:

- `mandown` creates a numbered footnote for the reference of the link right under it (inline in the text), with formatting that we can't influence,
- the **NOTES** section does not contain a visible link in the man page
- software (like `mdbook`) can render HTML with clickable links (inline in the text, which is not where we want it)

When using **[formatting links](https://example.org/formatting-links.html)**

- `mandown` creates a numbered footnote for the reference of the link right under it (inline in the text), with formatting that we can't influence,
- we can not add a link in the **NOTES** section
- software (like `mdbook`) can render HTML with clickable links (inline in the text, which is not where we want it)

Looking at the auto-numbering of links it appears as if `mandown` creates them for specific link types only.
This unfortunately doesn't mix too well with custom footnote numbering.

# NOTES

1. **Simple, manual link reference**

   https://example.org/simple.html

2. **angle-bracket URLS**

   <https://example.org/angle-bracket.html>

3. **reference-style links**

   [reference-style links]: https://example.org/reference.html

4. **formatting links**

   no way to add a link here, as it is added inline above!

example.7

example.7.html

example.7.md