Add configuration for readthedocs.org

readthedocs.org is switching to in-repo configuration file in favor of
the deprecated web interface as it allows more flexibility.

This also fixes our recent doc build issues, as we're switching to a
newer Python which is required by Sphinx.

See https://blog.readthedocs.com/migrate-configuration-v2/

.readthedocs.yaml

@@ -0,0 +1,20 @@
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+version: 2
+
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.11"
+
+# Build documentation in doc/arm/ with Sphinx
+sphinx:
+  configuration: doc/arm/conf.py
+
+# Build all formats
+formats: all
+
+# Explicitly set the version of Python and its requirements
+python:
+   install:
+   - requirements: doc/arm/requirements.txt

.reuse/dep5

@@ -163,6 +163,7 @@ Files: **/.clang-format
        .gitlab-ci.yml
        .lgtm.yml
        .pylintrc
+       .readthedocs.yaml
        .tsan-suppress
        .uncrustify.cfg
        doc/misc/*.zoneopt