macrodoc: remove unsupported references to @#then

macroprocessor.tex

@@ -65,7 +65,7 @@
     \begin{itemize}
     \item file inclusion
     \item loops (\textit{for} structure)
-    \item conditional inclusion (\textit{if/then/else} structures)
+    \item conditional inclusion (\textit{if/else} structures)
     \item expression substitution
     \end{itemize}
   \item Implemented in Dynare starting from version 4.0
@@ -95,7 +95,7 @@
     \begin{itemize}
     \item file inclusion: \verb+@#include+
     \item definition a variable of the macro-processor: \verb+@#define+
-    \item conditional statements (\verb+@#if/@#then/@#else/@#endif+)
+    \item conditional statements (\verb+@#if/@#else/@#endif+)
     \item loop statements (\verb+@#for/@#endfor+)
     \end{itemize}
   \item In most cases, directives occupy exactly one line of text. In case of need, two anti-slashes (\verb+\\+) at the end of the line indicates that the directive is continued on the next line.