docs: Add M4 MacBook Air (13" and 15", 2025) to feature support

Add the newly released M4 MacBook Air to the M4 devices table in the
feature support documentation. The MacBook Air 13-inch (Mac16,12) and
15-inch (Mac16,13) were announced March 5, 2025 and released March 12,
2025.

Features are marked as TBA consistent with other M4 devices that don't
yet have installer support. HDMI Out and SD card slot are marked as "-"
since MacBook Air does not have these ports.

Closes #237

Author: ericrowan

docs/platform/feature-support/m4.md

@@ -62,25 +62,25 @@ These are features/hardware blocks that are present on all devices with the give
 
 
 ## M4 devices
-|                    | MacBook Pro<br>(14-inch, Nov 2024)  | MacBook Pro<br>(16-inch, Nov 2024) |
-|--------------------|:-----------------------------------:|:----------------------------------:|
-| Installer          | no                                  | no                                 |
-| Devicetree         | TBA                                 | TBA                                |
-| Main display       | TBA                                 | TBA                                |
-| Keyboard           | TBA                                 | TBA                                |
-| KB backlight       | TBA                                 | TBA                                |
-| Touchpad           | TBA                                 | TBA                                |
-| Brightness         | TBA                                 | TBA                                |
-| Battery info       | TBA                                 | TBA                                |
-| WiFi               | TBA                                 | TBA                                |
-| Bluetooth          | TBA                                 | TBA                                |
-| HDMI Out           | TBA                                 | TBA                                |
-| 3.5mm jack         | TBA                                 | TBA                                |
-| Speakers           | TBA                                 | TBA                                |
-| Microphones        | TBA                                 | TBA                                |
-| Webcam             | TBA                                 | TBA                                |
-| SD card slot       | TBA                                 | TBA                                |
-| TouchID            | TBA                                 | TBA                                |
+|                    | MacBook Pro<br>(14-inch, Nov 2024)  | MacBook Pro<br>(16-inch, Nov 2024) | MacBook Air<br>(13" and 15" 2025) |
+|--------------------|:-----------------------------------:|:----------------------------------:|:---------------------------------:|
+| Installer          | no                                  | no                                 | no                                |
+| Devicetree         | TBA                                 | TBA                                | TBA                               |
+| Main display       | TBA                                 | TBA                                | TBA                               |
+| Keyboard           | TBA                                 | TBA                                | TBA                               |
+| KB backlight       | TBA                                 | TBA                                | TBA                               |
+| Touchpad           | TBA                                 | TBA                                | TBA                               |
+| Brightness         | TBA                                 | TBA                                | TBA                               |
+| Battery info       | TBA                                 | TBA                                | TBA                               |
+| WiFi               | TBA                                 | TBA                                | TBA                               |
+| Bluetooth          | TBA                                 | TBA                                | TBA                               |
+| HDMI Out           | TBA                                 | TBA                                | -                                 |
+| 3.5mm jack         | TBA                                 | TBA                                | TBA                               |
+| Speakers           | TBA                                 | TBA                                | TBA                               |
+| Microphones        | TBA                                 | TBA                                | TBA                               |
+| Webcam             | TBA                                 | TBA                                | TBA                               |
+| SD card slot       | TBA                                 | TBA                                | -                                 |
+| TouchID            | TBA                                 | TBA                                | TBA                               |
 
 ## M4 Pro/Max devices
 |                    | Mac mini<br>(2024) | MacBook Pro<br>(14-inch, Nov 2024)  | MacBook Pro<br>(16-inch, Nov 2024) |