Updates cowboy_http documents changelog
Updates cowboy_http documents changelog

The changelog had a wrong reference to an option that was updated.
`max_header_request_line_length` -> `max_request_line_length`

CrankWheel/cowboy,bsmr-erlang/cowboy,rabbitmq/cowboy,turtleDeng/cowboy,ninenines/cowboy,kivra/cowboy,hairyhum/cowboy,K2InformaticsGmbH/cowboy