remove `example` folder in this repo

[yibeichan]

@satra do we still need this folder? since we have reproschema-demo repo and the cookie-cutter, maybe we can remove it?

[satra]

do you have examples of all those concepts anywhere? neither of those two other repos have responses as examples. and i think it's useful to have examples as data as opposed to examples just in text/docs. these examples were also being used for testing/validation. so having a set of examples can serve multiple purposes.

[Remi-Gau]

in that case I would suggest exposing them directly in the doc otherwise they are harder to find for the user

[yibeichan]

okay, we can keep them as they are right now but add a pointer in the documentation, so users can find them. or we can keep them directly in the doc. let me see which one is easier