Show "links not implemented" only once

[Archelyst]

I think it would be enough to only warn once about links being not yet implemented. Right now it kinda spams the console.

[Chapabu]

I'm using this module as part of a Daemon, so it would be nice to have an option to not show this message at all as well. Perhaps it could read NODE_ENV and only show it on non-production environments?

Thinking about it, does it even need to show at all? Would a note in the README suffice?

[ucarbehlul]

What does it even mean? Can it be replaced with something more clear?

[Archelyst]

@ucarbehlul , see https://jsonapi.org/format/#document-links for the meaning of "links". This feature is not supported, i.e. the "links" property is ignored.