DOCSP-35031 $toHashedIndexKey results not collated (#7064) (#7407)

* DOCSP-35031  results not collated

* adjusts text

* adjusts text

* adjusts text

Author: kennethdyer

source/reference/operator/aggregation/toHashedIndexKey.txt

@@ -20,6 +20,13 @@ Definition
    A hash function maps a key or string to a fixed-size numeric 
    value.
 
+   .. note::
+
+      Unlike hashed indexes, the ``$toHashedIndexKey``
+      aggregation operator does **not** account for collation.
+      This means the operator can produce a hash that does not
+      match that of a hashed index based on the same data.
+
 Syntax
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