Update readthedocs.yml to v2 configuration file.

.readthedocs.yml

@@ -1,10 +1,18 @@
+version: 2
 formats: []
 
 build:
   image: latest
 
+sphinx:
+  configuration: docs/conf.py
+  fail_on_warning: false
+  builder: html
+
 python:
-  version: 3.6
+  version: 3.7
-  pip_install: true
+   install:
-  extra_requirements:
+    - method: pip
-    - docs
+      path: .
+      extra_requirements:
+          - docs