STYLE: Add braces around \input argument for consistency

Author: hjmjohnson

SoftwareGuide/Latex/Introduction/Installation.tex

@@ -684,7 +684,7 @@ \subsection{Hello World!}
 \url{https://cmake.org/cmake-tutorial/}} and CMake online
 documentation\footnote{\url{https://cmake.org/documentation/}}.
 
-\input HelloWorld.tex
+\input{HelloWorld.tex}
 
 By this point you have successfully configured and compiled ITK, and created
 your first simple program! If you have experienced any difficulties while