Add custom value transcoder example
Add custom value transcoder example

jackc/pgx,jackc/pgx,josephglanville/pgx,deoxxa/pgx,axsy-dev/tern,silviucm/pgx,plopik/pgx,jackc/tern,silviucm/pgx,jackc/pgx,plopik/pgx,silviucm/pgx,kelvich/pgx,rsto/pgx,plopik/pgx,jackc/tern-deb,jonasi/pgx,jackc/pgx