DOCS-10671 - Expand key description for shardCollection command

Author: jeff-allen-mongo

source/includes/apiargs-dbcommand-shardCollection-field.yaml

@@ -11,8 +11,20 @@ type: string
 ---
 arg_name: field
 description: |
-  The index specification document to use as the shard key. The shard
-  key determines how MongoDB distributes the documents among the shards.
+  The index specification document to use as the
+  :doc:`shard key </core/sharding-shard-key/>`. The shard key
+  determines how MongoDB distributes the documents among the shards.
+
+  The *key* of the index specification document is the field to use as
+  the shard key. The *value* of the document must be one of the
+  following:
+
+  - ``1`` to indicate forward traversal for the field.
+
+  - ``-1`` to indicate reverse traversal for the field.
+
+  - ``"hashed"`` to specify a
+    :ref:`hashed shard key <hashed-shard-keys>`.
 
   Unless the collection is empty, the index must exist prior to the
   :dbcommand:`shardCollection` command. If the collection is empty,
@@ -48,7 +60,7 @@ description: |
   shard key <sharding-hashed-sharding>`. MongoDB will then create and
   balance chunks across the cluster. The ``numInitialChunks`` must be
   less than ``8192`` per shard.
- 
+
   .. versionchanged:: 3.4
 
      If the collection is not empty or the shard key is not a hashed

source/reference/command/shardCollection.txt

@@ -61,11 +61,14 @@ Choosing the best shard key to effectively distribute load among your
 shards requires some planning. Review :ref:`sharding-shard-key`
 regarding choosing a shard key and restrictions.
 
+.. _hashed-shard-keys:
+
 Hashed Shard Keys
 ~~~~~~~~~~~~~~~~~
 
 :ref:`Hashed shard keys <sharding-hashed-sharding>` use a
-hashed index of a single field as the shard key.
+:doc:`hashed index </core/index-hashed/#index-hashed-index>` of a
+single field as the shard key.
 
 Use the form ``{field: "hashed"}`` to specify a hashed shard key.
 Hashed shard keys may not be compound indexes.