colon is added

"predict"  10 => "predict" : 10

docs/reference/aggregations/pipeline/movavg-aggregation.asciidoc

@@ -363,7 +363,7 @@ as your buckets:
             "buckets_path": "the_sum",
             "window" : 30,
             "model" : "simple",
-            "predict" 10
+            "predict" : 10
         }
 }
 --------------------------------------------------
@@ -445,4 +445,4 @@ minimization is linear to the size of the window being processed: excessively la
 Finally, minimization fits the model to the last `n` values, where `n = window`.  This generally produces
 better forecasts into the future, since the parameters are tuned around the end of the series.  It can, however, generate
 poorer fitting moving averages at the beginning of the series.
-======
+======