docs: remove limitation of 64 devices on aarch64

Remove the documentation note regarding the 64-device limit on aarch64,
as this limitation was resolved by an earlier commit.

The limitation no longer applies, and the documentation is now updated.

Signed-off-by: Sheng-Wei (Way) Chen <waychensw@gmail.com>

Author: Swchexit

docs/device-api.md

@@ -125,12 +125,6 @@ specification:
 |                        | track_dirty_pages |    O     |       O        |      O       |        O         |     O      |      O       |
 |                        | vcpu_count        |    O     |       O        |      O       |        O         |     O      |      O       |
 
-## Known device limitations
-
-If more than 64 devices are configured for a VM in total on aarch64, only first
-64 of them are functional
-([related issue](https://github.com/firecracker-microvm/firecracker/issues/4207)).
-
 ## Instance Actions
 
 All instance actions can be found in the [Swagger](https://swagger.io)