Update README.md
Add information about the repositories.
Change-Id: Iea95a4b2b37b2f351b9031e28b0906dc403adee5
diff --git a/README.md b/README.md
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--- a/README.md
+++ b/README.md
@@ -6,3 +6,23 @@
```
$ ./fetch_externals.py
```
+
+The script will build following tree structure.
+
+```
+Directory Repository
+. https://review.mlplatform.org/admin/repos/ml/ethos-u/ethos-u
++-- core_software https://review.mlplatform.org/admin/repos/ml/ethos-u/ethos-u-core-driver
+| +-- core_driver https://review.mlplatform.org/admin/repos/ml/ethos-u/ethos-u-core-software
+| +-- cmsis GitHub
+| +-- tensorflow GitHub
++-- vela https://review.mlplatform.org/admin/repos/ml/ethos-u/ethos-u-vela
+```
+
+| Directory | Description |
+--- | ---
+| . | This is the root directory for all Ethos-u software. |
+| core_software | The software executing on Arm Cortex-M is referred to as _Core Software_. This folder provides a small build system that illustrates how to build the key components for the Ethos-u core software. |
+| cmsis | CMSIS provides optimized kernels and generic interfaces to the Arm Cortex-M CPUs. |
+| tensorflow | The TensorFlowLite micro framework is used to run inferences. |
+| vela | The Vela optimizer takes a TFLu file as input and replaces operators that are supported by the Ethos-u NPU with custom operators designed to run on the NPU. Operators not supported by the NPU are executed in software. |