user friendly config file

[Shi-Ho]

Split between parameters for

• beginners (enable/disable, models name from a list, choice of auto-index)
• advanced (temperature, top_p, similarity metric, etc)

The goal is to have a less "scary" config.yaml that is easy to config.

OR

remove optional parameters from the config files and assign them default value in sourcecode (cf. Sphinx or MKDocs config file as exemple, can be started with a very minimal config.yaml)