fix a bunch of spelling errors
(closes SF patch #1104868)
diff --git a/Doc/lib/tkinter.tex b/Doc/lib/tkinter.tex
index 6a60982..f944eab 100644
--- a/Doc/lib/tkinter.tex
+++ b/Doc/lib/tkinter.tex
@@ -731,7 +731,7 @@
Screen distances can be specified in either pixels or absolute
distances. Pixels are given as numbers and absolute distances as
strings, with the trailing character denoting units: \code{c}
-for centimeters, \code{i} for inches, \code{m} for millimeters,
+for centimetres, \code{i} for inches, \code{m} for millimetres,
\code{p} for printer's points. For example, 3.5 inches is expressed
as \code{"3.5i"}.