Update Sphinx

Fix font licensing

Add spelling dict tests

Remove sphinx docs which were duplicated everywhere, refer to ONF main
docs site which is more complete

Add code of conduct and link

Change-Id: I35764345f09a4dcb082a73d4a1c0c04ce889c4a3
diff --git a/_static/css/rtd_theme_mods.css b/_static/css/rtd_theme_mods.css
index e449bde..e161fbe 100644
--- a/_static/css/rtd_theme_mods.css
+++ b/_static/css/rtd_theme_mods.css
@@ -1,17 +1,7 @@
 /*
- * Copyright 2019-present Open Networking Foundation
- *
- * 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
- *
- * http://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-FileCopyrightText: 2021 Open Networking Foundation <info@opennetworking.org>
+ * SPDX-License-Identifier: Apache-2.0
+ */
 
 /* Don't restrict content width on the RTD theme
  * from: https://stackoverflow.com/a/32898444 */