Align the TERM_MAPPING purpose example with the term mapping purpose values

https://specifications.openehr.org/releases/RM/latest/data_types.html#_term_mapping_class The purpose mentions as examples 'automated data mining', 'billing', 'interoperability'. https://specifications.openehr.org/releases/TERM/latest/SupportTerminology.html#_term_mapping_purpose The terminology list for term_mapping_purpose includes: 'public health', 'reimbursement' and 'research study'