Add corpus facet to library

Please add a facet to the library that will allow the user to see what works exist in a particular system defined corpus e.g. • Corpus: The noncanonical corpora analyzed and curated for this dataset include: • Apostolic Fathers • Dead Sea Scrolls Sectarian Material • Old Testament Pseudepigrapha • Nag Hammadi Codices • New Testament Apocrypha • Works of Josephus • Works of Philo