Fix/val-247 readme adjustments

[Ghesselink]

Add new up-to-date README files outputting the same data as in the frontend of the vs service (instance_id, expected, observed).
Additionally, a modified script to automatically generate this format is added.

Future to-do; the behave output conversion to tabulate/pytest is perhaps a bit outdated and could use a lick of paint.

[Ghesselink]

Added a couple of commits :

• Update markdown generator. It's not always straightforward to get the output message (which is a string representation of ValidationOutcome) back to a dict in a generic way. I think it's working better now.
• Add a script to create a readme file for all rules with one command (python test/run_generate_markdown.py)
• Disabled the disabled rules from generating.
• Run the previous mentioned script once to generate markdown README.md files

Changes addressed