Added rtd yaml config file

.readthedocs.yaml

@@ -0,0 +1,23 @@
+# Copyright 2023 OpenHW Group
+# Solderpad Hardware License, Version 2.1, see LICENSE.md for details.
+# SPDX-License-Identifier: Apache-2.0 WITH SHL-2.1
+
+# Read the Docs configuration file
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+# Required
+version: 2
+
+build:
+  os: "ubuntu-20.04"
+  tools:
+    python: "3.9"
+
+# Build from the docs directory with Sphinx
+sphinx:
+  configuration: doc/conf.py
+
+# Explicitly set the Python requirements
+python:
+  install:
+    - requirements: doc/requirements.txt