DOCSP-25081 Document --json flag for the mongosh CLI (#322)

* DOCSP-25081 Document --json flag for the mongosh CLI

* Update source/includes/examples/ex-eval-json.rst

Co-authored-by: Anna Henningsen <[email protected]>

* DOCSP-25081 updates for NV's feedback

---------

Co-authored-by: Anna Henningsen <[email protected]>

Author: kanchana-mongodb

source/includes/examples/ex-eval-json.rst

@@ -0,0 +1,9 @@
+To return statistics about a collection in Extended JSON format using
+multiple ``--eval`` statements: 
+
+.. code-block:: sh
+
+   mongosh --quiet --json=relaxed \
+           --eval 'use <database-name>' \
+           --eval 'db.<collection>.stats()' \
+           mongodb://localhost/

source/reference/options.txt

@@ -37,14 +37,25 @@ General Options
    statements, ``mongosh`` only prints the results of the last
    ``--eval``.
 
+   You can use the ``--json`` flag with ``--eval`` to return
+   ``mongosh`` results in :manual:`Extended JSON 
+   </reference/mongodb-extended-json/>` format. ``mongosh``
+   supports both ``--json=canonical`` and ``--json=relaxed`` modes. If
+   you omit the mode, ``mongosh`` defaults to the ``canonical``
+   mode. The ``--json`` flag is mutually exclusive with ``--shell``.
+
    **Example: Format Output**
 
    .. include:: /includes/examples/ex-eval-output.rst
 
-   **Example: Multiple ``--eval`` Arguments**
+   **Example: Multiple --eval Arguments**
 
    .. include:: /includes/examples/ex-eval-multi.rst
 
+   **Example: --json Option**
+
+   .. include:: /includes/examples/ex-eval-json.rst
+
 .. option:: --file, -f <javascript>
 
    Runs a script from the command line without entering the
@@ -77,7 +88,8 @@ General Options
    command and specify a JavaScript file as an argument, or use
    :option:`--eval <--eval>` to specify JavaScript on the command line,
    the :option:`--shell <--shell>` option provides the user with a shell
-   prompt after the file finishes executing.
+   prompt after the file finishes executing. The ``--shell`` flag is
+   mutually exclusive with ``--json``.  
 
 .. option:: --verbose