Add AMDPAL Code Conventions section to AMD docs
Add AMDPAL Code Conventions section to AMD docs

Summary:
This is a first version of the AMDPAL code conventions.
Further updates will undoubtably be required to fully
document AMDPAL.

Subscribers: nhaehnle, llvm-commits

Differential Revision: https://reviews.llvm.org/D45246

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@329188 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm