ci(readthedocs): configure builds for RTD build of project

I technically didn't configure things for social previews yet,
so fingers closed.

Signed-off-by: Andrei Jiroh Halili <ajhalili2006@andreijiroh.eu.org>

.readthedocs.yaml

@@ -0,0 +1,20 @@
+# Read the Docs configuration file for MkDocs projects
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+# Required
+version: 2
+
+# Set the version of Python and other tools you might need
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.11"
+    nodejs: 18
+
+mkdocs:
+  configuration: mkdocs.yml
+
+# Optionally declare the Python requirements required to build your docs
+python:
+  install:
+  - requirements: requirements.txt