[SPIR-V] Time to update the Inline SPIR-V wiki

[devshgraphicsprogramming]

Description

There are now new attributes for declaring SPIR-V builtins, etc.

But no documentation how to use them yet.

[Keenuts]

@cassiebeckley shall I assign this one to you?

[cassiebeckley]

Ah yes, I've had that on my agenda for a while

[Keenuts]

thanks!