Add section about things to know when upgrading Vulkan minor versions

[sfricke-samsung]

When going from 1.0 -> 1.1 or 1.1 -> 1.2 there are some slight "gotchas" that would be great to document somewhere. Most things would be around the subtle promotion changes that are not always obvious at first glance.

One thing, that prompted this idea, is the Extension Feature Aliases table in the spec and things to know about using certain new promoted extensions/features.

This would probably go into the Version chapter