Unprecise documentation on extended function semantics

[antoine-gallix]

I stumbled mentions on extended function semantics and went to this section of the doc: https://funcy.readthedocs.io/en/stable/extended_fns.html#extended-fns

IMHO, this section could use some examples. For example it states that providing a mapping instead of a callable would result in lambda x: f[x] being used. It took me some time to figure out how to use this just by reading this dry description.

Would you be interested that I complete this page a bit with usage examples?

[Suor]

Examples will help for sure. I have them in some function docs but not here. Will be grateful if you'll full this in. Maybe something akin to the overview.