Document `msgpack.object:index`

[TarantoolBot]

Related dev. issue(s): tarantool/tarantool#7898

Product: Tarantool
Since: 2.11
Root document: https://www.tarantool.io/en/doc/latest/reference/reference_lua/msgpack/
SME: @ CuriousGeorgiy

Details

For the API description and usage exmaples, see design document.

Requested by @ CuriousGeorgiy in tarantool/tarantool@dcc3fcd.