DOCSP-23004: Clarifications for MozJS Upgrade (#1167)

* add clarifiction for static vs prototype functions

* add sentence

* clarity

* Update source/release-notes/6.0-compatibility.txt

Co-authored-by: Justin Seyster <[email protected]>

* further clarity

Co-authored-by: Justin Seyster <[email protected]>

Author: jeff-allen-mongo

source/includes/fact-6.0-js-engine-change.rst

@@ -1,5 +1,6 @@
 MongoDB 6.0 upgrades the internal JavaScript engine used for
 :ref:`server-side JavaScript <server-side-javascript>`,
 :group:`$accumulator`, :expression:`$function`, and :query:`$where`
-expressions and from MozJS-60 to MozJS-91. Several non-standard array
-and string functions that existed in MozJS-60 are removed in MozJS-91.
+expressions and from MozJS-60 to MozJS-91. Several deprecated,
+non-standard array and string functions that existed in MozJS-60 are
+removed in MozJS-91.

source/release-notes/6.0-compatibility.txt

@@ -306,11 +306,29 @@ will receive an error message like the following:
 
 .. _6.0-js-engine-change:
 
-Removed Array and String Functions for Server-Side JavaScript
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Removed Deprecated Array and String Functions for Server-Side JavaScript
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 .. include:: /includes/fact-6.0-js-engine-change.rst
 
+For the complete list of removed array and string functions, see the
+next sections on this page.
+
+.. note:: Only Static Functions are Removed
+
+   Only *static* JavaScript functions are removed. *Prototype function*
+   equivalents of the removed functions can still be used.
+
+   For example:
+
+   - ``Array.concat(<array1>, <array2>)`` is a static function and no
+     longer works in MongoDB 6.0.
+   - ``<array1>.concat(<array2>)`` is a prototype function and still
+     works in MongoDB 6.0.
+
+   This behavior applies to both removed array and removed string
+   functions.
+
 Removed Array Functions
 ```````````````````````