Updated Windows command to add correct way to add go to the systems P…

…ATH environment variable

go-intro.tex

@@ -165,7 +165,7 @@ \section{Getting Go for Windows}
 created when you unpacked the zip;
 \item Add \verb|C:\Go\bin| to your \$PATH:
 \begin{display}
-export PATH=\verb|C:\Go\bin|
+set PATH=\verb|%PATH%;C:\Go\bin|
 \end{display}
 \end{itemize}