[Config] Document the 'replication.anon' option

[andreyaksenov]

Product: Tarantool
Since: 3.0
Root document: #3664
SME: @ totktonada

Details

Old content: https://www.tarantool.io/en/doc/latest/reference/configuration/#cfg-replication-replication-anon

[andreyaksenov]

Duplicates #3896.