Bug #1603789: grammatical error in Tkinter docs.

(backport from rev. 52850)

Doc/lib/tkinter.tex

@@ -318,7 +318,7 @@ the name of a widget.
 \item[\var{options}]
 configure the widget's appearance and in some cases, its
 behavior.  The options come in the form of a list of flags and values.
-Flags are proceeded by a `-', like \UNIX{} shell command flags, and
+Flags are preceded by a `-', like \UNIX{} shell command flags, and
 values are put in quotes if they are more than one word.
 \end{description}