Update documentation

manual/command-reference-manual.tex

@@ -7407,6 +7407,10 @@ in order to avoid a name collision with the built in commands.
 
 If any arguments are specified, these arguments are provided to the script via
 the standard $argc and $argv variables.
+
+Note, tcl will not recieve the output of any yosys command. If the output
+of the tcl commands are needed, use the yosys command 'tee' to redirect yosys's
+output to a temporary file.
 \end{lstlisting}
 
 \section{techmap -- generic technology mapper}