Set up automated Flux commands reference

[fsteeg]

Like flux-commands.md (which is basically the output of sh flux.sh > flux-commands.md, see https://github.com/metafacture/metafacture-core/commit/4d80ab4a87eed552fb36de722765c2f1ae6e7923), but:

• [ ] Improve flux-commands.md content (group commands by type, explain signatures -> https://github.com/metafacture/metafacture-documentation/issues/16, add missing options) -> https://github.com/metafacture/metafacture-core/issues/367
• [ ] Automated creation and publishing of flux-commands.md with GitHub Actions (triggered by metafacture-core releases) -> https://github.com/metafacture/metafacture-core/issues/368
• [ ] Add filtering support, e.g. generate filter 'buttons' for each type as input and output, e.g. ->StreamReceiver for all decoders, StreamReceiver-> for all encoders, etc. -> https://github.com/metafacture/metafacture-core/issues/369

[TobiasNx]

Sorting of the list perhaps should be sorted by input not by alphabet.