Document how to log with JSON format

[hmpf]

Scope and purpose

Allows structured logs controlled by us.

This does not change any code, and it's use optional.

This pull request

• adds/changes/removes a dependency

Contributor Checklist

Every pull request should have this checklist filled out, no matter how small it is.
More information about contributing to Argus can be found in the
Development docs.

• Added a changelog fragment for towncrier
• Added/amended tests for new/changed code
• Added/changed documentation, including updates to the user manual if feature flow or UI is considerably changed
• Linted/formatted the code with ruff and djLint, easiest by using pre-commit
• The first line of the commit message continues the sentence "If applied, this commit will ...", starts with a capital letter, does not end with punctuation and is 50 characters or less long. See our how-to
• If applicable: Created new issues if this PR does not fix the issue completely/there is further work to be done
• If this results in changes in the UI: Added screenshots of the before and after
• If this results in changes to the database model: Updated the ER diagram

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

Test results

    8 files  1 712 suites   3m 7s ⏱️
  933 tests   932 ✅ 1 💤 0 ❌
7 464 runs  7 456 ✅ 8 💤 0 ❌

Results for commit 761a966.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.60%. Comparing base (7c04efb) to head (761a966).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1929   +/-   ##
=======================================
  Coverage   88.60%   88.60%           
=======================================
  Files         146      146           
  Lines        7093     7093           
=======================================
  Hits         6285     6285           
  Misses        808      808           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[aleksfl]

Not much to comment, instructions and dependency work when tested.