docs: migrate new struct content to md docs (DOCS-3240) (#4326)

* docs: migrate new struct content to md docs (DOCS-3240)

* docs: remove inline struct content for .rst

* docs: restore inline struct content for .rst

docs-md/developer-guide/syntax-reference.md

@@ -84,9 +84,19 @@ SELECT address->city, address->zip FROM orders;
 
 For more info, see [Operators](#operators).
 
-!!! note
-      You can't create new nested `STRUCT` data as the result of a query, but
-      you can copy existing `STRUCT` fields as-is.
+You can create a `STRUCT` in a query by specifying the names of the columns
+and expressions that construct the values, separated by commas. The following
+example SELECT statement creates a schema that has a `STRUCT`.
+
+```sql
+SELECT STRUCT(name := col0, ageInDogYears := col1*7) AS dogs FROM animals
+```
+
+If `col0` is a string and `col1` is an integer, the resulting schema is:
+
+```sql
+col0 STRUCT<name VARCHAR, ageInDogYears INTEGER>
+```
 
 ### ksqlDB Time Units
 

docs/developer-guide/syntax-reference.rst

@@ -71,13 +71,6 @@ encapsulate a street address and a postal code:
      orderId BIGINT,
      address STRUCT<street VARCHAR, zip INTEGER>) WITH (...);
 
-
-You can create a struct in a query by specifying the names of the columns
-and expressions that construct the values, separated by ``,`` and wrapped with
-curly braces. For example: ``SELECT STRUCT(name := col0, ageInDogYears := col1*7) AS dogs FROM animals``
-creates a schema ``col0 STRUCT<name VARCHAR, ageInDogYears INTEGER>``, assuming ``col0`` was a string and
-``col1`` was an integer.
-
 Access the fields in a ``STRUCT`` by using the dereference operator (``->``):
 
 .. code:: sql
@@ -86,8 +79,19 @@ Access the fields in a ``STRUCT`` by using the dereference operator (``->``):
 
 For more info, see :ref:`operators`.
 
-.. note:: You can’t create new nested ``STRUCT`` data as the result of a query,
-   but you can copy existing ``STRUCT`` fields as-is.
+You can create a ``STRUCT`` in a query by specifying the names of the columns
+and expressions that construct the values, separated by commas. The following
+example SELECT statement creates a schema that has a ``STRUCT``.
+
+.. code:: sql
+
+   SELECT STRUCT(name := col0, ageInDogYears := col1*7) AS dogs FROM animals
+
+If ``col0`` is a string and ``col1`` is an integer, the resulting schema is:
+
+.. code:: sql
+
+   col0 STRUCT<name VARCHAR, ageInDogYears INTEGER>
 
 .. _ksql-time-units: