As per deprecation here: https://blog.readthedocs.com/migrate-configuration-v2/

csparpa · csparpa · commit 3be796cc60fd · 2023-06-24T13:50:42.000+02:00
diff --git a/.readthedocs.yaml b/.readthedocs.yaml
@@ -1,4 +1,4 @@
-# .readthedocs.yml
+# .readthedocs.yaml
 # Read the Docs configuration file
 # See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
 

Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,4 @@`
`1`		`-# .readthedocs.yml`
	`1`	`+# .readthedocs.yaml`
`2`	`2`	`# Read the Docs configuration file`
`3`	`3`	`# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details`
`4`	`4`