update © year for user manual

doc/userman/main.tex

@@ -37,7 +37,7 @@ CEA LIST\\ Software Safety \& Security Laboratory
 \end{center}
 \vfill
 \begin{flushleft}
-  \textcopyright 2013-2020 CEA List
+  \textcopyright 2013-2022 CEA List
 %%
   %% This work has been supported by the VESSEDIA project).
 \end{flushleft}