Enable a 'Key Theorist' label to be added to resources that are old but foundational

To enhance how reading lists can support the development of students' information literacy skills (particuarly among first-years), it would be useful if resources could be tagged/labelled as 'Key Theorist'.

This would indicate to students that the resource is on the list due to the currency/ importance/ relevance of its content/theory despite how old it is.

eg. Freud, Vygotsky, Darwin etc.

This would unclutter 'Notes to Students' and enhance the pedagogical potential of lists.