21.05 release

Adding externals configuration for 21.05 release. Updating README.md
with instructions how to download the release.

Change-Id: I81d53818a2a5cd22b530bef6a08770ceba0134f3
diff --git a/21.05.json b/21.05.json
new file mode 100644
index 0000000..00c0220
--- /dev/null
+++ b/21.05.json
@@ -0,0 +1,65 @@
+{
+    "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": "21.05"
+        },
+        {
+            "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": "21.05"
+        },
+        {
+            "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": "21.05"
+        },
+        {
+            "path": "core_software/cmsis",
+            "fetchurl": "https://github.com/ARM-software/CMSIS_5.git",
+            "revision": "e9637de2b4cfd99cd5c93893d88593262d8660c1"
+        },
+        {
+            "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": "20210526_Archive"
+        },
+        {
+            "path": "core_software/rtos/freertos/freertos_kernel",
+            "fetchurl": "https://github.com/FreeRTOS/FreeRTOS-Kernel.git",
+            "revision": "V10.4.3"
+        },
+        {
+            "path": "core_software/tensorflow",
+            "fetchurl": "https://github.com/tensorflow/tensorflow",
+            "revision": "v2.5.0"
+        },
+        {
+            "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": "21.05"
+        },
+        {
+            "path": "linux_driver_stack/flatbuffers",
+            "fetchurl": "https://github.com/google/flatbuffers",
+            "revision": "v2.0.0"
+        },
+        {
+            "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": "3.0.0"
+        }
+    ]
+}
diff --git a/README.md b/README.md
index 485b9a7..6da8b4c 100644
--- a/README.md
+++ b/README.md
@@ -16,7 +16,7 @@
 example.
 
 ```
-$ ./fetch_externals.py -c 21.02.json fetch
+$ ./fetch_externals.py -c 21.05.json fetch
 ```
 
 ## Directory structure