doc: boards: add Cubieboard7 documentation

This adds build and flash steps for Actions S700
based Cubieboard7 board.

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Amit Singh Tomar <amittomer25@gmail.com>
diff --git a/doc/board/actions/index.rst b/doc/board/actions/index.rst
new file mode 100644
index 0000000..c596879
--- /dev/null
+++ b/doc/board/actions/index.rst
@@ -0,0 +1,10 @@
+.. SPDX-License-Identifier: GPL-2.0+
+.. Copyright (C) 2020 Amit Singh Tomar <amittomer25@gmail.com>
+
+Actions
+========
+
+.. toctree::
+   :maxdepth: 2
+
+   cubieboard7