Update converter docs

[ischoegl]

Changes proposed in this pull request

• fix links in converter script (convert and main are valid links)
• use Sphinx 'note' directives for improved browsing

Checklist

• [x] The pull request includes a clear description of this code change
• [x] Commit messages have short titles and reference relevant issues
• [x] Build passes (scons build & scons test) and unit tests address code coverage
• [x] Style & formatting of contributed code follows contributing guidelines
• [x] The pull request is ready for review

[ischoegl]

Instead of the generic note, you can also use the seealso admonition, which is specifically styled by pydata-sphinx-theme (https://pydata-sphinx-theme.readthedocs.io/en/stable/examples/kitchen-sink/admonitions.html)

Great suggestion! Wasn't aware of this admonition, but it fits perfectly.