MLECO-1860: Support for Arm GNU Embedded Toolchain

This patch enables compilation of ML use cases bare-metal applications
using Arm GNU Embedded Toolchain. The GNU toolchain can be used instead
of the Arm Compiler that was already supported.

The GNU toolchain is also set as the default toolchain when building
applications for the MPS3 target.

Note: The version of GNU toolchain must be 10.2.1 or higher.

Change-Id: I5fff242f0f52d2db6c75d292f9fa990df1aec978
Signed-off-by: Kshitij Sisodia <kshitij.sisodia@arm.com>
diff --git a/release_notes.txt b/release_notes.txt
index abf605b..1b2ced7 100644
--- a/release_notes.txt
+++ b/release_notes.txt
@@ -2,14 +2,16 @@
     * Added script to download and optimize default models.
     * Added script to run default build flow.
     * Added a model for Anomaly Detection use case.
+    * added support for build with Arm GNU Embedded Toolchain (10.2.1).
+    * deprecated support for target subsystem SSE-200.
 
 Changes in 21.03
-    * simple platform support added
-    * model conditioning examples added
-    * documentation updated
-    * build changed to use sources of the dependency libraries
-    * tests for native platform added
-    * anomaly detection use case added
+    * simple platform support added.
+    * model conditioning examples added.
+    * documentation updated.
+    * build changed to use sources of the dependency libraries.
+    * tests for native platform added.
+    * anomaly detection use case added.
 
 Changes in 20.11
     * SSE-200 and SSE-300 system support was added.