fix auto insertion warnings

[xuwei-k]

[warn] -- Warning: /home/runner/work/playframework.com/playframework.com/app/actors/DocumentationActor.scala:564:17 
[warn] 564 |            .map(DocumentationSitemap)
[warn]     |                 ^^^^^^^^^^^^^^^^^^^^
[warn]     |The method `apply` is inserted. The auto insertion will be deprecated, please write `actors.DocumentationActor.DocumentationSitemap.apply` explicitly.
[warn] -- Warning: /home/runner/work/playframework.com/playframework.com/app/controllers/documentation/DocumentationController.scala:2[64](https://github.com/playframework/playframework.com/actions/runs/16085402790/job/45395893285#step:12:65):13 
[warn] 264 |    (actor ? GetSummary).mapTo[DocumentationSummary].map { summary =>
[warn]     |             ^^^^^^^^^^
[warn]     |The method `apply` is inserted. The auto insertion will be deprecated, please write `actors.DocumentationActor.GetSummary.apply` explicitly.
[warn] -- Warning: /home/runner/work/playframework.com/playframework.com/app/controllers/documentation/DocumentationController.scala:293:13 
[warn] 293 |    (actor ? GetSitemap).mapTo[DocumentationSitemap].map { docSitemap =>
[warn]     |             ^^^^^^^^^^
[warn]     |The method `apply` is inserted. The auto insertion will be deprecated, please write `actors.DocumentationActor.GetSitemap.apply` explicitly.