[Kaleidoscope][BuildingAJIT] Add tutorial text for Chapter 2.

This chapter discusses IR optimizations, the ORC IRTransformLayer, and the ORC
layer concept itself.

The text is still pretty rough, but I think the main ideas are there. Feedback
is very welcome, as always.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@271865 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed