Merge pull request #4205 from rouault/fix_4202

Doc: prepare for ReadTheDocs Deprecation: Removal of Sphinx context injection at build time

docs/source/conf.py

@@ -267,3 +267,14 @@
 
 source_file_root = os.path.join(os.path.dirname(__file__), os.pardir, os.pardir)
 source_file_url_template = "https://github.com/OSGeo/PROJ/blob/master/{}"
+
+# -- Specifics when documentation is built on ReadTheDocs infra
+
+# Cf https://about.readthedocs.com/blog/2024/07/addons-by-default
+
+# Define the canonical URL if you are using a custom domain on Read the Docs
+html_baseurl = os.environ.get("READTHEDOCS_CANONICAL_URL", "")
+
+# Tell Jinja2 templates the build is running on Read the Docs
+if os.environ.get("READTHEDOCS", "") == "True":
+    html_context["READTHEDOCS"] = True