Update index.md (#8340) (#8342)

Signed-off-by: Naarcha-AWS <97990722+Naarcha-AWS@users.noreply.github.com>
(cherry picked from commit 81a1355)

_tuning-your-cluster/index.md

@@ -198,9 +198,11 @@ To further fine-tune your shard allocation, you can set custom node attributes f
 
 You can set custom node attributes on OpenSearch nodes to be used for shard allocation awareness. For example, you can set the `zone` attribute on each node to represent the zone in which the node is located. You can also use the `zone` attribute to ensure that the primary shard and its replica shards are allocated in a balanced manner across available, distinct zones. For example, maximum shard copies per zone would equal `ceil (number_of_shard_copies/number_of_distinct_zones)`.
 
-Shard allocation awareness attempts to separate primary and replica shards across multiple zones because 2 shard copies cannot be placed on the same node. When only 1 zone is available, such as after a zone failure, OpenSearch allocates replica shards to the only remaining zone. For example, if your index has a total of 5 shard copies (1 primary and 4 replicas) and nodes in 3 distinct zones, then OpenSearch will perform the following to allocate all 5 shard copies: 
+OpenSearch, by default, allocates shard copies of a single shard across different nodes. When only 1 zone is available, such as after a zone failure, OpenSearch allocates replica shards to the only remaining zone---it considers only available zones (attribute values) when calculating the maximum number of allowed shard copies per zone.
 
-- Allocate fewer than 2 shards per zone, which will require at least 2 nodes in 2 zones.
+For example, if your index has a total of 5 shard copies (1 primary and 4 replicas) and nodes in 3 distinct zones, then OpenSearch will perform the following to allocate all 5 shard copies:
+
+- Allocate no more than 2 shards per zone, which will require at least 2 nodes in 2 zones.
 - Allocate the last shard in the third zone, with at least 1 node needed in the third zone.
 
 Alternatively, if you have 3 nodes in the first zone and 1 node in each remaining zone, then OpenSearch will allocate: