revise wording to avoid confusion for non-native English speakers

Doc/tut/tut.tex

@@ -689,7 +689,7 @@ sliced.
 \begin{verbatim}
 >>> word[:2]    # The first two characters
 'He'
->>> word[2:]    # All but the first two characters
+>>> word[2:]    # Everything except the first two characters
 'lpA'
 \end{verbatim}