Typo in PK migration guide

\copy history_old TO '/tmp/history.csv' DELIMITER ',' CSV
       CREATE TEMP TABLE temp_history (
           itemid                   bigint                                    NOT NULL,
           clock                    integer         DEFAULT '0'               NOT NULL,
           value                    DOUBLE PRECISION DEFAULT '0.0000'          NOT NULL,
           ns                       integer         DEFAULT '0'               NOT NULL
       );
       \copy temp_history FROM '/tmp/history.csv' DELIMITER ',' CSV
       INSERT INTO history_uint SELECT * FROM temp_history ON CONFLICT (itemid,clock,ns) DO NOTHING;

       INSERT INTO history SELECT * FROM temp_history ON CONFLICT