Docs: Restructure the documents

Restructure the file category to let it more friendly to users.

Signed-off-by: Summer Qin <summer.qin@arm.com>
Change-Id: I7ced0e2d700ce03423e472e0098608f3445ba169
diff --git a/docs/technical_references/index.rst b/docs/technical_references/index.rst
new file mode 100644
index 0000000..bd7c572
--- /dev/null
+++ b/docs/technical_references/index.rst
@@ -0,0 +1,15 @@
+Technical References
+====================
+
+.. toctree::
+    :maxdepth: 2
+    :titlesonly:
+    :glob:
+    :numbered:
+
+    */index
+    *
+
+--------------
+
+*Copyright (c) 2020, Arm Limited. All rights reserved.*