Depth buffering chapter documentation completely different from actual code

[SaschaWillems]

While working on #134 I also wanted to update the documentation for the depth buffering chapter. But said documentation is completely different than the actual code. Functions names do not match, calls are made in the documentation, but not the code, documentation mixes C/C++ header style, documentation uses some code to automatically deduce barrier settings, etc.

@gpx1000: What should we do in such cases? I need to adjust barriers in code, but the documentation does not resemble the code, so unsure on how to or if at all I can/should also update the documentation.

[johannes-el]

This also partially applies to the Image view and sampler chapter. For example, the old tutorial still had a function bool isDeviceSuitable(VkPhysicalDevice device). Now this function is still used in this particular chapter but has not been introduced prior to it.