Parameter settability backport 4.2 (#1027)

* DOCS-15069 getParameter exposes settability for server params (#553)

* command to expose settability for server params

* review feedback

* updates description of "*"

* addresses duplicate target name getParameter-showdetails-all-params

* fixes merge conflict

Author: jmd-mongo

source/reference/command/getParameter.txt

@@ -41,17 +41,31 @@ getParameter
 
       * - ``getParameter``
 
-        - int, ``'*'``
+        - int, string, document
 
         - Specify a value of:
 
-          - ``'*'`` to return all parameters available to
-            :dbcommand:`getParameters`, ignoring the ``<parameter>`` field.
-          
-          - any numerical value to return the value for the specified
-            ``<parameter>``.
+          - ``1`` (or any integer value) to return the value for the 
+            specified ``<parameter>``.
 
+          - ``'*'`` to return values for all parameters available to
+            :dbcommand:`getParameter`, ignoring the ``<parameter>`` field.
+
+          - ``{ showDetails: true }`` to return a document containing:
+            
+            .. _showdetails-fields:
+
+            - ``value``, the value that ``<parameter>`` is set to
+            - ``settableAtRuntime``, whether or not ``<parameter>`` can 
+              be set at runtime
+            - ``settableAtStartup``, whether or not ``<parameter>`` can
+              be set at startup  
 
+          - ``{ showDetails: true, allParameters: true }`` to return a 
+            document containing :ref:`showDetails fields 
+            <showdetails-fields>` for **all** parameters.
+
+
 
       * - ``<parameter>``
 
@@ -116,4 +130,45 @@ The following operation runs :dbcommand:`getParameter` with a value of
 
 .. seealso:: :dbcommand:`setParameter` for more about these parameters.
 
-   .. slave-ok, admin-only
+.. _getParameter-showdetails-single-param:
+
+Report Details on a Single Parameter
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The following example runs :dbcommand:`getParameter` with 
+``{showDetails: true}`` to report :ref:`details <showdetails-fields>` 
+on :parameter:`saslHostName`.
+
+.. code-block:: javascript
+   
+   db.adminCommand( { getParameter : { showDetails: true }, "saslHostName" : 1 } )
+  
+Example output:
+
+.. code-block:: javascript
+   :copyable: false
+
+   {
+     saslHostName: {
+       value: '<hostname>',
+       settableAtRuntime: false,
+       settableAtStartup: true
+     },
+     ok: 1
+   }
+
+.. include:: /includes/note-output-may-vary.rst
+
+
+.. _getParameter-showdetails-all-params:
+
+Report Details for All Parameters
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The following example runs :dbcommand:`getParameter` with 
+``{showDetails: true, allParameters: true}`` to report 
+:ref:`details <showdetails-fields>` on **all** parameters.
+
+.. code-block:: javascript
+   
+   db.adminCommand( { getParameter : { showDetails: true, allParameters: true } } )