docs: various updates and text fixes in HTML for MD conversion

[neteler]

This PR contains various HTML updates and textual fixes in preparation for the planned markdown conversion (see also #4748).

For this PR, I have (briefly) reviewed all ~600 GRASS GIS manual pages by converting them to MD for a quality check, and then updated the original HTML files accordingly. Thus it is also a backport candidate for G84.

Changes in detail:

• adding missing intro sentences
• added module name in the first sentence where missing
• http -> https
• selected URL updates for broken URLs
• selected additions in "SEE ALSO" sections
• fix suboptimal HTML formatting (flags, special names, ...)
• add missing keywords on metapages
• remove leftover Last changed: $Date$ entries from CVS/SVN days
• simplify selected -<dl><dt>... to <ul><li>... for improved MD conversion
• replaced <tt>...</tt> with <code>...</code>

For an easier review, the changes have been submitted in separate commits:

• db: 473b95b
• display: fca42da
• doc: e473bc8
• general: 00930f5
• gui: e9259cf
• imagery: e700a7c, c888dba
• lib: 6da27ca
• misc: bfa7c0d
• raster: 0c5ca83
• raster3d: 0c44c95
• scripts: e5bd683, 7b70b03
• temporal: a173a8f
• vector: b5167fa
• visualization: 81e9756

Extra changes:

• replaced <tt>...</tt> with <code>...</code> in 14841b2
• dot product: replaced . with · f8ea200
• review by @echoix: 1645685 and 6fd0a66
• utils/g.html2man/htmltags.txt: dropped outdated file (see instead utils/g.html2man/ggroff.py) in 92597b2

[echoix]

Ok, I'm getting bored, but didn't finish going through all lychee detections/false positives

I ran:

./lychee . --suggest --require-https --archive wayback --base file:///home/vscode/grass/dist.x86_64-pc-linux-gnu/docs/html/ --output lychee_output.md --cache --i
nclude-fragments --include-verbatim --format markdown --cache-exclude-status '429, 500..502'

The output of what I was working on:
lychee_output3.md

The same output after I worked on:
lychee_output4.md

The cache file, two versions in case it is useful (list of links):
lycheecache.zip

A dump of links, created with

./lychee . --suggest --require-https --archive wayback  --include-fragments  --dump --output lychee_dump.txt  --mode plain

lychee_dump.txt

In case someone would want to reproduce the same commands with cache, I added (temporarily) these lines in the .gitignore so the cache/result files wouldn't have their links extracted too:

.lycheecache
lychee
lychee-x86_64-unknown-linux-musl.tar.gz
lychee_output.md
lychee_output

[neteler]

g.setproj doesn't seem to be built/available online in 8.4 and 8.5, and also 7.8, 7.0. It exists for 6.4 and 6.5 https://grass.osgeo.org/grass64/manuals/g.setproj.html

Google search for "grass g.setproj" links to 6.5

Right: g.setproj is essentially unneeded code as g.proj has taken over (many years ago it was discussed in the grass-dev list to keep it for easier lookup of code-chunks but I'd suggest to rather remove it in a separate PR). I see a few mentions in messages like d.*, g.region and wxGUI wizard, though (to be updated as well then).

[neteler]

What is the correct URL for "Internet: http://grass.osgeo.org/home/contact-us/" in https://github.com/neteler/grass/blob/0be2b97149407d76add9346d207ff52eb205a530/doc/development/rfc/legal_aspects_of_code_contributions.md#L69? It is dead, http, and I don't seem to find the equivalent. (It is not a html file, but it appeared in the search for http only links).

The closest page seems to be https://grass.osgeo.org/about/team/ - what do you think, @veroandreo ?

[veroandreo]

What is the correct URL for "Internet: http://grass.osgeo.org/home/contact-us/" in https://github.com/neteler/grass/blob/0be2b97149407d76add9346d207ff52eb205a530/doc/development/rfc/legal_aspects_of_code_contributions.md#L69? It is dead, http, and I don't seem to find the equivalent. (It is not a html file, but it appeared in the search for http only links).

The closest page seems to be https://grass.osgeo.org/about/team/ - what do you think, @veroandreo ?

There is no contact info on the team page. Why not either https://grass.osgeo.org/support/community/ or Discourse directly?

[neteler]

The closest page seems to be https://grass.osgeo.org/about/team/ - what do you think, @veroandreo ?

There is no contact info on the team page. Why not either https://grass.osgeo.org/support/community/ or Discourse directly?

Okay, updated in a9938d7

[neteler]

Seems we are ready to go?

[echoix]

Since what could be remaining is fine tuning dead links with archives, and that would be a never ending endeavour, I think that what needed to be fixed in here is fixed, and it improves on the previous state.

So yes, I think this should go as is