fix: DOC-843: Update tutorial (#1212)

https://deephaven.atlassian.net/browse/DOC-843

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Co-authored-by: Joe <[email protected]>

Author: margaretkennedy

plugins/ui/docs/tutorial.md

@@ -691,8 +691,6 @@ ui_iris_avg = ui.panel(iris_avg, title="Average")
 ui_iris_max = ui.panel(iris_max, title="Max")
 ui_iris_min = ui.panel(iris_min, title="Min")
 
-ui.stack(ui_iris_avg, ui_iris_max, ui_iris_min) = ui.stack(ui_iris_avg, ui_iris_max, ui_iris_min)
-
 species_table = iris.view("Species").select_distinct()
 
 def create_sepal_panel(set_species):