DOCSP-34413 mongodump Regex Syntax (#5307) (#5357)

* DOCSP-34413 mongodump Regex Syntax

* update note w/ quote syntax rules

* remove redundant links

* split up paragraph

* JM feedback

Author: ajhuh-mdb

source/reference/operator/query/regex.txt

@@ -41,14 +41,29 @@ Compatibility
 Syntax
 ------
 
-To use :query:`$regex`, use one of the following syntaxes:
+To use ``$regex``, use one of the following syntaxes:
 
 .. code-block:: javascript
 
    { <field>: { $regex: /pattern/, $options: '<options>' } }
-   { <field>: { $regex: 'pattern', $options: '<options>' } }
+   { "<field>": { "$regex": "pattern", "$options": "<options>" } }
    { <field>: { $regex: /pattern/<options> } }
 
+.. note:: 
+
+   To use ``$regex`` with :binary:`~bin.mongodump`, you must enclose the query 
+   document in single quotes ('{ ... }') to ensure that it does not interact 
+   with your shell environment. 
+   
+   The query document must be in :ref:`Extended JSON v2 
+   <mongodb-extended-json-v2>` format (either relaxed or canonical/strict mode), 
+   which includes enclosing the field names and operators in quotes. For 
+   example:
+
+   .. code-block:: sh
+
+      mongodump -d=sample_mflix -c=movies  -q='{"year": {"$regex": "20"}}'
+
 In MongoDB, you can also use regular expression objects (i.e.
 ``/pattern/``) to specify regular expressions:
 
@@ -96,7 +111,7 @@ expression.
    * - ``x``
 
      - "Extended" capability to ignore all white space characters in
-       the :query:`$regex` pattern unless escaped or included in a
+       the ``$regex`` pattern unless escaped or included in a
        character class.
 
        Additionally, it ignores characters in-between and including
@@ -121,7 +136,7 @@ expression.
 
 .. note:: 
 
-   The :query:`$regex` operator does not support the global search
+   The ``$regex`` operator does not support the global search
    modifier ``g``.
 
 Behavior
@@ -143,14 +158,14 @@ only use JavaScript regular expression objects (i.e. ``/pattern/``
 
    { name: { $in: [ /^acme/i, /^ack/ ] } }
 
-You *cannot* use :query:`$regex` operator expressions inside an
-:query:`$in`.
+You *cannot* use ``$regex`` operator expressions inside an
+:query:`$in` operator.
 
 Implicit ``AND`` Conditions for the Field
 `````````````````````````````````````````
 
 To include a regular expression in a comma-separated list of query
-conditions for the field, use the :query:`$regex` operator. For example:
+conditions for the field, use the ``$regex`` operator. For example:
 
 .. code-block:: javascript
 
@@ -162,7 +177,7 @@ conditions for the field, use the :query:`$regex` operator. For example:
 ```````````````````````
 
 To use either the ``x`` option or ``s`` options, you must use the
-:query:`$regex` operator expression *with* the :query:`$options`
+``$regex`` operator expression *with* the :query:`$options`
 operator. For example, to specify the ``i`` and the ``s`` options, you
 must use :query:`$options` for both:
 
@@ -175,7 +190,7 @@ PCRE Versus JavaScript
 ``````````````````````
 
 To use {+pcre-abbr+}-supported features in a regular expression that
-aren't supported in JavaScript, you must use the :query:`$regex`
+aren't supported in JavaScript, you must use the ``$regex``
 operator and specify the regular expression as a string.
 
 To match case-insensitive strings:
@@ -194,7 +209,7 @@ These strings match the example regular expression:
 - ``"acme"``
 - ``"Acme"``
 
-The following example uses the :query:`$regex` operator to find ``name``
+The following example uses the ``$regex`` operator to find ``name``
 field strings that match the regular expression ``"(?i)a(?-i)cme"``:
 
 .. code-block:: javascript
@@ -217,7 +232,7 @@ operation on both:
 
      db.inventory.find( { item: { $not: /^p.*/ } } )
 
-- :query:`$regex` operator expressions 
+- ``$regex`` operator expressions 
 
   For example:
 
@@ -358,7 +373,7 @@ Without the ``m`` option, the example output is:
       { _id: 104, sku: 'Abc789', description: 'SKU starts with A' }
    ]
 
-If the :query:`$regex` pattern does not contain an anchor, the pattern
+If the ``$regex`` pattern does not contain an anchor, the pattern
 matches against the string as a whole, as in the following example:
 
 .. code-block:: javascript