Revert "Platform: Remove Musca_A platform code (Deprecation)"

This reverts commit a29d6695749aedb4015320af18e782b85744600a.

Reason for revert: Musca-A is still a reference platform for 1 user.

Change-Id: I3a96d5157677390360aaa82eac96b9810db58c43
diff --git a/docs/introduction/readme.rst b/docs/introduction/readme.rst
index a940ffd..8b0dd8e 100644
--- a/docs/introduction/readme.rst
+++ b/docs/introduction/readme.rst
@@ -125,6 +125,8 @@
           <https://developer.arm.com/products/system-design/development-boards/cortex-m-prototyping-systems/mps2>`_
         - `Fast model FVP_MPS2_AEMv8M (AN521).
           <https://developer.arm.com/products/system-design/fixed-virtual-platforms>`_
+        - `Musca-A test chip board.
+          <https://developer.arm.com/products/system-design/development-boards/iot-test-chips-and-boards/musca-a-test-chip-board>`_
         - `Musca-B1 test chip board.
           <https://developer.arm.com/products/system-design/development-boards/iot-test-chips-and-boards/musca-b-test-chip-board>`_
         - `Musca-S1 test chip board.