[petrasovaa]

fatra.cnr.ncsu.eduis being retired. skagit.meas.ncsu.edu was retired long time ago. This replaces/removes every reference to them in the tool documentation.

• DOIs where the cited work has one (11 papers across v.surf.rst, v.vol.rst, r.flow, r.fillnulls, r.watershed, r.sim.water,
  r.sim.sediment)
• Wayback for the r.sun Trento 2002 proceedings paper, which has no DOI — pointed at the original conference site rather than the personal-page copy
• Removed links that pointed at pages rather than papers: lab and personal homepages, a dead GIScience 2000 talk page, and a v.vol.rst entry with no bibliographic detail and no archived copy

Also drops raster/r.carve/README, whose content is in r.carve.md except an outdated parameter list (rast=/vect=, now raster=/vector=).

Each .md and its .html were updated together.

One case I was not sure is the commented out documentation for r.fill.stats describing the creation of the image. It's not in the md file, so it will eventually be removed with the html anyway. It can be always found in history if needed, so I removed it.

Commit message

The fatra.cnr.ncsu.edu server is being retired and skagit.meas.ncsu.edu
was retired long ago. This replaces or removes every reference to them
in the tool documentation:

- Use DOIs where the cited work has one (11 papers across v.surf.rst,
  v.vol.rst, r.flow, r.fillnulls, r.watershed, r.sim.water, and
  r.sim.sediment).
- Use a Wayback Machine link for the r.sun Trento 2002 proceedings
  paper, which has no DOI. The link goes to the original conference
  site, not the copy on a personal page.
- Remove links that pointed to pages rather than papers: lab and
  personal homepages, a dead GIScience 2000 talk page, and a v.vol.rst
  entry with no bibliographic details and no archived copy.

Remove raster/r.carve/README. Its content is already in r.carve.md,
apart from an outdated parameter list (rast= and vect= instead of the
current raster= and vector=).

Remove the commented-out notes on creating the image in
r.fill.stats.html. They are not in r.fill.stats.md, so they would be
dropped with the HTML file later anyway, and they remain in the Git
history.

Each .md file and its .html file were updated together.

[wenzeslaus]

I spot checked some of the links and I agree with the removal of the bigger blocks and some of the links. For others, I made separate comments with opt-in action.