[Docs] Add revision date to rendered docs (#21752)

Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>

.readthedocs.yaml

@@ -7,6 +7,9 @@ build:
   os: ubuntu-22.04
   tools:
     python: "3.12"
+  jobs:
+    post_checkout:
+      - git fetch --unshallow || true
 
 mkdocs:
   configuration: mkdocs.yaml