Align docu in 07_Depth_buffering.adoc with source in 27_depth_buffering.cpp

[asuessenbach]

No description provided.

[asuessenbach]

Don't know why the windows-latest build fails.
It says:

CMake Error at C:/Program Files/CMake/share/cmake-3.31/Modules/FindPackageHandleStandardArgs.cmake:233 (message):
  Could NOT find KTX (missing: KTX_INCLUDE_DIR KTX_LIBRARY)
Call Stack (most recent call first):
  C:/Program Files/CMake/share/cmake-3.31/Modules/FindPackageHandleStandardArgs.cmake:603 (_FPHSA_FAILURE_MESSAGE)
  CMake/FindKTX.cmake:55 (find_package_handle_standard_args)
  C:/vcpkg/scripts/buildsystems/vcpkg.cmake:908 (_find_package)
  CMakeLists.txt:20 (find_package)

Anything I can do to make the CI happy here?