Fix doc about max number of failing zone (#9512)

* Fix doc about max number of failing zone

* Update docs/sources/mimir/configure/configure-zone-aware-replication.md

Co-authored-by: Nick Pillitteri <56quarters@users.noreply.github.com>

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Co-authored-by: Nick Pillitteri <56quarters@users.noreply.github.com>

docs/sources/mimir/configure/configure-zone-aware-replication.md

@@ -71,7 +71,7 @@ With a replication factor of 3, which is the default, deploy the Grafana Mimir c
 Deploying Grafana Mimir clusters to more zones than the configured replication factor does not have a negative impact.
 Deploying Grafana Mimir clusters to fewer zones than the configured replication factor can cause writes to the replica to be missed, or can cause writes to fail completely.
 
-If there are fewer than `floor(replication factor / 2)` zones with failing replicas, reads and writes can withstand zone failures.
+A Grafana Mimir deployment should have at least `floor(replication factor / 2) + 1` healthy zones to operate.
 
 ## Unbalanced zones