(DOCS-16446) Changes initial minimum number of chunks per shard for empty collections (#5216)

* (DOCS-16446) Changes initial minimum number of chunks per shard for empty collections

* Includes copy review changes

Author: sarahsimpers

source/core/hashed-sharding.txt

@@ -147,20 +147,19 @@ Sharding Empty Collection on Single Field Hashed Shard Key
   - With no :ref:`zones and zone ranges <zones-sharding>` specified 
     for the empty or non-existing collection:
 
-    - The sharding operation creates empty chunks to cover the entire
-      range of the shard key values and performs an initial chunk
-      distribution. By default, the operation creates 2 chunks per shard
-      and migrates across the cluster. You can use ``numInitialChunks``
-      option to specify a different number of initial chunks. This
-      initial creation and distribution of chunks allows for faster
-      setup of sharding.
+    - The sharding operation creates an empty chunk to cover the entire
+      range of the shard key values. Starting in version 7.2, the
+      operation creates 1 chunk per shard by default and migrates
+      across the cluster. You can use ``numInitialChunks`` option to
+      specify a different number of initial chunks and cause an initial
+      chunk distribution. This initial creation and distribution of
+      chunks allows for faster setup of sharding.
 
     - After the initial distribution, the balancer manages the chunk
       distribution going forward.
 
   - With zones and zone ranges specified
-    for the empty or a non-existing collection (Available starting in 
-    MongoDB 4.0.3):
+    for the empty or a non-existing collection:
 
     - The sharding operation creates empty chunks for the defined zone
       ranges as well as any additional chunks to cover the entire range
@@ -173,19 +172,20 @@ Sharding Empty Collection on Single Field Hashed Shard Key
 
 Sharding Empty Collection on Compound Hashed Shard Key with Hashed Field Prefix
   If the compound hashed shard key has the hashed field as the prefix
-  (i.e. the hashed field is the first field in the shard key):
+  (the hashed field is the first field in the shard key):
 
   - With no zones and zone ranges specified 
     for the empty or non-existing collection:
 
     - The sharding operation creates empty chunks to cover the entire
       range of the shard key values and performs an initial chunk
       distribution. The value of all non-hashed fields is :bsontype:`MinKey` at
-      each split point. By default, the operation creates 2 chunks per
-      shard and migrates across the cluster. You can use
-      ``numInitialChunks`` option to specify a different number of
-      initial chunks. This initial creation and distribution of chunks
-      allows for faster setup of sharding.
+      each split point. Starting in version 7.2, the operation creates
+      1 chunk per shard by default and migrates across the cluster. You
+      can use ``numInitialChunks`` option to specify a different number
+      of initial chunks and cause an initial chunk distribution. This
+      initial creation and distribution of chunks allows for faster
+      setup of sharding.
 
     - After the initial distribution, the balancer manages the chunk
       distribution going forward.