Fix doc warnings.

8358e801 · Arnaud Bergeron · a51d2d4a · 8358e801
--- a/doc/tutorial/using_gpu.txt
+++ b/doc/tutorial/using_gpu.txt
@@ -370,7 +370,7 @@ Consider again the logistic regression:

 .. testoutput::
   :hide:
-   :options: + ELLIPSIS
+   :options: +ELLIPSIS

   Used the cpu
   target values for D