Release validation for v4.0

[mossmaurice]

Website/Markdown settings

• Add .markdownlint.yaml file
• move fonts to the root folder and symlink them from everywhere else
  • explore whether the same can be done with the assets
• split images into a root folder with common images and one for the specific versions for the rendered SVGs

Examples

• Rework icedelivery
  • Explain lifetime semantics of chunks/samples and user restrictions: loan needs to be followed with publish or release, MAX_CHUNKS_IN_USE on publisher and subscriber side etc., API is not thread-safe, update asciinema record (@MatthiasKillat)

New articles

• How to write integration tests
• Performance results section

Last tasks