replication: removing anonymous replicas from synchro quorum

[art-dr]

Since: 2.10.0-beta2
Root document: https://www.tarantool.io/en/doc/latest/book/replication/repl_sync/#usage
SME: @ kyukhin
dev issue: tarantool/tarantool#5418

Details

In tarantool/tarantool@04b2230 it is said that "Transactions should be committed after they reach quorum of "real" cluster members. Therefore, anonymous replicas shouldn't participate in the quorum"

Documentation says: "This option tells how many replicas should confirm the receipt of a synchronous transaction before it is committed. So far, this option accounts for all replicas including anonymous ones."

Correct the text so it says that anonymous replicas don't participate in the quorum since 2.10.0.