message: memo: documented Xcode 8.3
diff: @@ -744,6 +744,7 @@ The following compilers are currently used in continuous integration at [Travis]
  | Clang Xcode 8.0 | Darwin Kernel Version 15.6.0 | Apple LLVM version 8.0.0 (clang-800.0.38) |
  | Clang Xcode 8.1 | Darwin Kernel Version 16.1.0 (macOS 10.12.1) | Apple LLVM version 8.0.0 (clang-800.0.42.1) |
  | Clang Xcode 8.2 | Darwin Kernel Version 16.1.0 (macOS 10.12.1) | Apple LLVM version 8.0.0 (clang-800.0.42.1) |
  +| Clang Xcode 8.3 | Darwin Kernel Version 16.5.0 (macOS 10.12.4) | Apple LLVM version 8.1.0 (clang-802.0.38) |
  | Visual Studio 14 2015 | Windows Server 2012 R2 (x64) | Microsoft (R) Build Engine version 14.0.25123.0 |
  | Visual Studio 2017 | Windows Server 2016 | Microsoft (R) Build Engine version 15.1.548.43366 |
  