Merge pull request #16 from tcal-x/rtd

Add .readthedocs.yml; don't load submodules.

.readthedocs.yml

@@ -0,0 +1,31 @@
+# Copyright (C) 2020  The SymbiFlow Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+# .readthedocs.yml
+# Read the Docs configuration file
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+version: 2
+
+sphinx:
+  configuration: docs/conf.py
+  fail_on_warning: true
+
+python:
+  version: 3.7
+  install:
+    - requirements: docs/requirements.txt