Create feature choice helper on narayana.io

It would be useful to have something on our homepage that lists all the different transports we use and what features are available when you select each of those transport. Mainly all features are available which allows us to list those too.

Ideally in the future it might replace our current landing page so we should try to include all details from that too where possible - so you could include an axis that said "commercial support available" STM = No, XTS = yes and so on.

Needs experimentation to see what will work best.