Man pages matching name mongoc_transaction_opts_set_read_prefs in section 3:

mongoc_transaction_opts_set_read_prefs.3.en	debian 10 / libmongoc-doc
mongoc_transaction_opts_set_read_prefs.3.en	debian 11 / libmongoc-doc
mongoc_transaction_opts_set_read_prefs.3.en	debian 12 / libmongoc-doc