docs: remove use of escape strings and use bytea hex output

docs:  remove use of escape strings and use bytea hex output

standard_conforming_strings defaulted to 'on' in PG 9.1.
bytea_output defaulted to 'hex' in PG 9.0.

Reported-by: André Hänsel
Discussion: https://postgr.es/m/12e601d447ac$345994a0$9d0cbde0[email protected]

Backpatch-through: 9.3