[2pt] "max_header_name_length" option is missed for http.client

Seems [here](https://github.com/tarantool/tarantool/commit/3d121dd4a82d4199e053b09a8059bf445240f749#diff-7050096f607c6e5a8e28553cca41bee1b57336b1cad5f0e1e41f2ca4429f847aR262-R265) this option was added. However I don't find any mention in our doc (https://www.tarantool.io/en/doc/latest/reference/reference_lua/http/#lua-function.client_object.request).