remove spurious line from widget variables example

(closes SF patch #1094815)

Doc/lib/tkinter.tex

@@ -621,7 +621,6 @@ class App(Frame):
         self.entrythingy = Entry()
         self.entrythingy.pack()
         
-        self.button.pack()
         # here is the application variable
         self.contents = StringVar()
         # set it to some value