Documentation error for `XR_VARJO_composition_layer_depth_test`

In the documentation for the `XR_VARJO_composition_layer_depth_test` extension, under the New Structures heading, it says the `XrCompositionLayerDepthTestVARJO` structure can be chained to the `XrCompositionLayerProjectionView` structure. This contradicts the rest of the extension documentation, as well as Varjos own plugins, where instead it is chained directly to the `XrCompositionLayerProjection` structure.

Start in the documentation for the XR_VARJO_composition_layer_depth_test extension and locate the New Structures section. Compare the stated chaining target with the rest of the extension documentation and Varjo's plugins, then correct the structure reference so it is consistent.

Written by the indexing model from the issue text.