Create dataset loader for PPR corpus

[davidkartchner]

Adding a Dataset

• Name: PPR Plant Phenotype Relation corpus
• Description: Dataset with plant and phenotype mentions, as well as relations of how plants/plant extracts affect the phenotypes
• Task: NER, RE
• Paper: Plant phenotype relationship corpus for biomedical relationships between plants and phenotypes
• Data: https://github.com/DMCB-GIST/PPRcorpus
• License: None
• Motivation: Plants and phenotypes are important for both drug discovery. This dataset also provides an strong benchmark for biomedical NER and RE tasks

[davidkartchner]

#self-assign