DOCSP-28645 Standardize release note landing page behavior (#6056)

Author: jeff-allen-mongo

snooty.toml

@@ -201,14 +201,17 @@ toc_landing_pages = [
    "/release-notes/4.4-downgrade",
    "/release-notes/4.4",
    "/release-notes/5.0",
+   "/release-notes/5.0-downgrade",
    "/release-notes/5.1",
    "/release-notes/5.2",
    "/release-notes/5.3",
    "/release-notes/6.0",
+   "/release-notes/6.0-downgrade",
    "/release-notes/6.1",
    "/release-notes/6.2",
    "/release-notes/6.3",
    "/release-notes/7.0",
+   "/release-notes/7.0-downgrade",
    "/release-notes/7.1",
    "/release-notes/7.2",
    "/release-notes/7.3",