21.08 release

Adding externals configuration for 21.08 release.

Updating README.md with instructions how to download the release.

Change-Id: I28c770dd1e7d258f1db9c9ad86a25680b868f322
diff --git a/21.08.json b/21.08.json
new file mode 100644
index 0000000..5d40838
--- /dev/null
+++ b/21.08.json
@@ -0,0 +1,70 @@
+{
+    "externals":
+    [
+        {
+            "path": "core_platform",
+            "fetchurl": "https://review.mlplatform.org/ml/ethos-u/ethos-u-core-platform",
+            "pushurl": "ssh://review.mlplatform.org:29418/ml/ethos-u/ethos-u-core-platform",
+            "revision": "21.08"
+        },
+        {
+            "path": "core_software",
+            "fetchurl": "https://review.mlplatform.org/ml/ethos-u/ethos-u-core-software",
+            "pushurl": "ssh://review.mlplatform.org:29418/ml/ethos-u/ethos-u-core-software",
+            "revision": "21.08"
+        },
+        {
+            "path": "core_software/core_driver",
+            "fetchurl": "https://review.mlplatform.org/ml/ethos-u/ethos-u-core-driver",
+            "pushurl": "ssh://review.mlplatform.org:29418/ml/ethos-u/ethos-u-core-driver",
+            "revision": "21.08"
+        },
+        {
+            "path": "core_software/cmsis",
+            "fetchurl": "https://github.com/ARM-software/CMSIS_5.git",
+            "revision": "c43379be65dec9d808b72b8efbe52cad762909be"
+        },
+        {
+            "path": "core_software/cmsis-view",
+            "fetchurl": "https://github.com/ARM-software/CMSIS-View.git",
+            "revision": "8dabfca313b88b93ca9afd1dd2454e29ba859a6a"
+        },
+        {
+            "path": "core_software/rtos/freertos",
+            "fetchurl": "https://github.com/aws/amazon-freertos.git",
+            "revision": "202107.00"
+        },
+        {
+            "path": "core_software/rtos/freertos/freertos_kernel",
+            "fetchurl": "https://github.com/FreeRTOS/FreeRTOS-Kernel.git",
+            "revision": "c290780e3464941e190db19e88d03979fb2b11d8"
+        },
+        {
+            "path": "core_software/rtos/threadx",
+            "fetchurl": "https://github.com/azure-rtos/threadx",
+            "revision": "v6.1.8_rel"
+        },
+        {
+            "path": "core_software/tflite_micro",
+            "fetchurl": "https://github.com/tensorflow/tflite-micro",
+            "revision": "4e091a46e935afcb27035e538044e37892d4a983"
+        },
+        {
+            "path": "linux_driver_stack",
+            "fetchurl": "https://review.mlplatform.org/ml/ethos-u/ethos-u-linux-driver-stack",
+            "pushurl": "ssh://review.mlplatform.org:29418/ml/ethos-u/ethos-u-linux-driver-stack",
+            "revision": "21.08"
+        },
+        {
+            "path": "linux_driver_stack/flatbuffers",
+            "fetchurl": "https://github.com/google/flatbuffers",
+            "revision": "db6eae5c429d6fd1fed67a4beb64258ab02aac98"
+        },
+        {
+            "path": "vela",
+            "fetchurl": "https://review.mlplatform.org/ml/ethos-u/ethos-u-vela",
+            "pushurl": "ssh://review.mlplatform.org:29418/ml/ethos-u/ethos-u-vela",
+            "revision": "3.1.0"
+        }
+    ]
+}
diff --git a/README.md b/README.md
index 6da8b4c..c9ed50f 100644
--- a/README.md
+++ b/README.md
@@ -16,7 +16,7 @@
 example.
 
 ```
-$ ./fetch_externals.py -c 21.05.json fetch
+$ ./fetch_externals.py -c 21.08.json fetch
 ```
 
 ## Directory structure