checkout: accord documentation to what git does

Signed-off-by: Nicolas Sebrecht <nicolas.s.dev@gmx.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-checkout.txt

diff --git a/Documentation/git-checkout.txt b/Documentation/git-checkout.txt
index 7146288..7b83162 100644
--- a/Documentation/git-checkout.txt
+++ b/Documentation/git-checkout.txt
@@ -238,7 +238,7 @@
 +
 ------------
 $ git checkout mytopic
-fatal: Entry 'frotz' not uptodate. Cannot merge.
+error: You have local changes to 'frotz'; not switching branches.
 ------------
 +
 You can give the `-m` flag to the command, which would try a