docs: Add thanks to all contributors to main README.md

[neteler]

Add an auto-generated section listing all contributors with their icons at the bottom of README.md.

Make this README.md file less boring :-)

Uses:
https://contrib.rocks/preview?repo=OSGeo%2Fgrass

[veroandreo]

beautiful ❤️

[marisn]

Oh no! How is possible that this got merged?!? As I have enabled pre-commit hook (thanks @nilason ) now I can not commit anything unless I change this code too – a no-no in the middle of a merge.
Either this code needs to be changed or pre-commit linters need an exception.

$ git commit
[INFO] Checking merge-conflict files only.
trim trailing whitespace.................................................Passed
fix end of files.........................................................Passed
markdownlint.............................................................Failed
- hook id: markdownlint
- exit code: 1

README.md:111 MD012/no-multiple-blanks Multiple consecutive blank lines [Expected: 1; Actual: 2]
README.md:114:2 MD033/no-inline-html Inline HTML [Element: a]
README.md:115:4 MD033/no-inline-html Inline HTML [Element: img]

black....................................................................Passed
flake8...................................................................Passed
clang-format.............................................................Passed
yamllint.................................................................Passed

[neteler]

Either this code needs to be changed or pre-commit linters need an exception.

Done both, see #2971

[wenzeslaus]

I think --no-verify is meant for these cases like merge of non-complaint files (SE).

[wenzeslaus]

... How is possible that this got merged?!? ...

...--no-verify is meant for these cases...

With that said, this should not happen. I understood that a check in CI is not possible yet because the not all files are compliant yet and doing only the "PR diff" is not readily available. Please, correct me if if I'm wrong, @nilason.

[nilason]

Temporarily disabling hooks: https://pre-commit.com/#temporarily-disabling-hooks

With that said, this should not happen.

To that I absolutely agree!

I understood that a check in CI is not possible yet because the not all files are compliant yet and doing only the "PR diff" is not readily available. Please, correct me if if I'm wrong, @nilason.

You're essentially right, but let me elaborate:

The main problem is that the superlinter, which checks (among others) markdown and yaml files are not in complete sync with the settings in .pre-commit-config.yaml. Furthermore, the trailing-whitespace check does not even have an equivalent, neither does the end-of-file-fixer check (the latter is however visible in GH code viewer as a stop sign).
The clang-format, black and flake8 checks are reliable however.

At the time I introduced pre-commit all files in repo were passing the checks (with the rules and exceptions in .pre-commit-config.yaml) in ordinary committing usage. It is not, however, possible to do a pre-commit run --all-files because the way pre-commit works in that mode: the .flake8 file is then not used and perhaps the black setting are also ignored.

I figured using superlinter is close enough (and considering its ease of use and with the main advantage to avoid unnecessary CI runs, everyone would use pre-commit anyway...), but close enough is obviously not good enough!

Back then I flagged for the the possible solution for this might be https://pre-commit.ci, but I haven't got to it to explore how that might be implemented.