Add a Read the Docs configuration file (#99)

This PR adds a config file for Read the Docs.

Author: mdickinson

.readthedocs.yaml

@@ -0,0 +1,18 @@
+# Read the Docs configuration file
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+version: 2
+
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.12"
+
+sphinx:
+  configuration: docs/source/conf.py
+
+python:
+  install:
+  - requirements: docs/requirements.txt
+  - method: pip
+    path: .