Man pages matching name tsmimehdrfieldvaluestringinsert in section 3ts:

TSMimeHdrFieldValueStringInsert.3ts.en	debian 10 / trafficserver-dev
TSMimeHdrFieldValueStringInsert.3ts.en	debian 11 / trafficserver-dev
TSMimeHdrFieldValueStringInsert.3ts.en	debian 12 / trafficserver-dev