SF bug #764616:  execfile(filename,...) not execfile(file,...)

Clarify parameter name.
diff --git a/Doc/lib/libfuncs.tex b/Doc/lib/libfuncs.tex
index 9d181b1..6b61d36 100644
--- a/Doc/lib/libfuncs.tex
+++ b/Doc/lib/libfuncs.tex
@@ -354,7 +354,7 @@
   \function{execfile()}.
 \end{funcdesc}
 
-\begin{funcdesc}{execfile}{file\optional{, globals\optional{, locals}}}
+\begin{funcdesc}{execfile}{filename\optional{, globals\optional{, locals}}}
   This function is similar to the
   \keyword{exec} statement, but parses a file instead of a string.  It
   is different from the \keyword{import} statement in that it does not