apacheGH-40799: [Doc][Format] Implementation status page should list …

…canonical extension types (apache#41053)

### Rationale for this change

Two specifications and one implementation of canonical extension types were added and this should be documented.

### What changes are included in this PR?

This represents current state of canonical extension types.

### Are these changes tested?

No, docs only.

### Are there any user-facing changes?

In so much as they read docs.
* GitHub Issue: apache#40799

Authored-by: Rok Mihevc <[email protected]>
Signed-off-by: Rok Mihevc <[email protected]>

docs/source/status.rst

@@ -111,14 +111,24 @@ Data Types
 | Run-End Encoded   | ✓     |       | ✓     |            |       |       |       |       |
 +-------------------+-------+-------+-------+------------+-------+-------+-------+-------+
 
++-----------------------+-------+-------+-------+------------+-------+-------+-------+-------+
+| Canonical             | C++   | Java  | Go    | JavaScript | C#    | Rust  | Julia | Swift |
+| Extension types       |       |       |       |            |       |       |       |       |
++=======================+=======+=======+=======+============+=======+=======+=======+=======+
+| Fixed shape tensor    | ✓     |       |       |            |       |       |       |       |
++-----------------------+-------+-------+-------+------------+-------+-------+-------+-------+
+| Variable shape tensor |       |       |       |            |       |       |       |       |
++-----------------------+-------+-------+-------+------------+-------+-------+-------+-------+
+
 Notes:
 
 * \(1) Casting to/from Float16 in Java is not supported.
 * \(2) Float16 support in C# is only available when targeting .NET 6+.
 * \(3) Nested dictionaries not supported
 
 .. seealso::
-   The :ref:`format_columnar` specification.
+   The :ref:`format_columnar` and the
+   :ref:`format_canonical_extensions` specification.
 
 
 IPC Format