DOC: Update supported compiler version information

Author: dzenanz

SoftwareGuide/Latex/Introduction/Installation.tex

@@ -34,8 +34,8 @@ \chapter{Configuring and Building ITK}
 %%
 \begin{itemize}
 \item GCC 7 and newer
-\item Visual Studio 2017 version 15.7 and newer
-\item Xcode 10.0 (Apple LLVM Clang version 10.0.0) and newer
+\item Visual Studio 2019 (technically MSVC toolset v142) and newer
+\item Xcode 10.0 (Apple Clang version 10.0.0, LLVM Clang 5) and newer
 \end{itemize}
 
 If you are currently using an outdated compiler this may be an excellent excuse