Add Push Constant chapter
@sfricke-samsung likewise this will require asciidoc conversion, which I will do, if you want.
@sfricke-samsung would you like me to rebase this / convert to asciidoctor markup, to move it along, or is it sufficiently out of date as to no longer be relevant?
So the original goal of this chapter was to answer the last section question of ## Pushing data with non-compatible layouts... the internal issue hit many problems and wasn't much energy to get it resolved
But looking at this, there is still some good content in here and I think it is probably worth rebasing and getting in
I can asciidoctor this btw, will probably just make a new PR because this fork is on my old account
@oddhack or @gpx1000 this can be closed now with https://github.com/KhronosGroup/Vulkan-Guide/pull/196 merged (I don't have access to my old account to close it myself)