Minor wording change on slicing aide-memoire.

Doc/tut/tut.tex

@@ -813,7 +813,7 @@ Traceback (most recent call last):
 IndexError: string index out of range
 \end{verbatim}
 
-The best way to remember how slices work is to think of the indices as
+One way to remember how slices work is to think of the indices as
 pointing \emph{between} characters, with the left edge of the first
 character numbered 0.  Then the right edge of the last character of a
 string of \var{n} characters has index \var{n}, for example: