Free endpoints

[hp0404]

This is something I should've started with,

As outlined in the docs, there are some free to use endpoints (as long as we respect ratelimits). Those include:

1. Papers - Retrieve paper metadata

• endpoints:
  • Get Paper (Get paper metadata for DOI) -- GET /papers/{doi}
  • Get Papers (Get multiple papers; up to 500 papers can be requested at once by passing in a list of DOIs) -- GET /papers
  • Get Papers by Target (Get papers citing a given DOI)-- GET /papers/sources/{target_doi}

2. Tallies - Retrieve scite smart citation tallies (not quite sure what it means)

• endpoints:
  • Get Tally (Get smart citation tally for given DOI) -- GET /tallies/{doi}
  • Get Tallies (Get multiple smart citation tallies; up to 500 papers can be requested at once by passing in a list of DOIs) -- GET /tallies

[hp0404]

I'll test Papers soon.
Once Stephan confirms it's worth spending time on, I'll write a proper wrapper around those endpoints.

[hp0404]

Hopefully, Tallies endpoints work the same (from the looks of it), and if so, I'll ask @bohdanbaliuk to jump in.

This one I think you should handle well on your own, but still please work in the separate branch -- like tally-endpoints -- and create pull request once you're ready.

[hp0404]

I'll create separate issues and assign tasks there. Just to keep it clean and well-organized