Clarify webbrowser.open description.

Doc/lib/libwebbrowser.tex

@@ -47,7 +47,7 @@ The following functions are defined:
 
 \begin{funcdesc}{open}{url\optional{, new=0\optional{, autoraise=1}}}
   Display \var{url} using the default browser. If \var{new} is 0, the
-  \var{url} is opened in the same browser window.  If \var{new} is 1,
+  \var{url} is opened in the same browser window if possible.  If \var{new} is 1,
   a new browser window is opened if possible.  If \var{new} is 2,
   a new browser page ("tab") is opened if possible.  If \var{autoraise} is
   true, the window is raised if possible (note that under many window