add stairwell expansion module and update misp-objects to a193e03

[goodlandsecurity]

• adding stairwell expansion module
• update misp-objects submodule to a193e03
• updated README and documentation accordingly

[adulau]

Thanks a lot. Could you add the JSON documentation of the module? It's how the module documentation are generated.

[goodlandsecurity]

Added, thank you for the reminder. It was hard to track down all the required doc files to add 😅

[adulau]

Awesome! Thank you very much for the contribution.