Add section/examples using data from Biodiversity Heritage Library

[wragge]

Get a BHL API Key: https://www.biodiversitylibrary.org/getapikey.aspx

API Docs: https://www.biodiversitylibrary.org/docs/api3.html

Endpoint: https://www.biodiversitylibrary.org/api3

Additionally, all of the data exports can be found on the BHL Open Data Collection alongside documentation and data dictionaries:
https://smithsonian.figshare.com/projects/Biodiversity_Heritage_Library_Open_Data_Collection/151911