Add .readthedocs.yaml (#136)

.readthedocs.yaml

+# 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: "3.8"
+
+sphinx:
+   configuration: docs/source/conf.py
+
+# If using Sphinx, optionally build your docs in additional formats such as PDF
+formats:
+   - pdf
+
+# Optionally declare the Python requirements required to build your docs
+python:
+   install:
+   - requirements: docs/requirements-docs.txt

docs/requirements-docs.txt

-sphinx
-sphinx-click
-sphinx-copybutton
+sphinx == 6.2.1
+sphinx-book-theme == 1.0.1
+sphinx-copybutton == 0.5.2