Fix markdown and relative links on github.io page

[e-kwsm]

README.md has the following relative links:

• [``dftd4(1)``](man/dftd4.1.adoc)
• [parameters.toml file](./assets/parameters.toml)
• [``python``](./python)

These work on GitHub, but do not on https://dftd4.github.io/dftd4/, e.g., https://dftd4.github.io/dftd4/man/dftd4.1.adoc does not exist.

I’m not sure if ford can prefix https://github.com/dftd4/dftd4/blob/main/.

[codecov]

Codecov Report

Merging #104 (0667abe) into main (750b3ce) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #104   +/-   ##
=======================================
  Coverage   60.01%   60.01%           
=======================================
  Files          39       39           
  Lines        2886     2886           
  Branches      979      979           
=======================================
  Hits         1732     1732           
  Misses        599      599           
  Partials      555      555           

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[awvwgk]

I see, that is unfortunate. I don't think ford supports custom prefixes, just adding the prefixes will break the relative links in branches and forks as well as in local previews, but getting the docs to link correctly seems more important.

In the long-term I'll have to look for a new documentation tool anyway, since ford development and maintenance has pretty much stalled.