Return several URLs

Currently /doc/pubmed/{} returns the URL for the PubMed record Web page.

Would be nice to also return the Entrez API, like this:

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=pubmed&id={}&rettype=xml

---

For /taxon/{}, same:

https://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=taxonomy&id={}&rettype=xml

ou

https://bacdive.dsmz.de/fetch/14702