Tutorial typo fix (due to renaming?) (#3250)
Tutorial typo fix (due to renaming?) (#3250)

I think this fixes a small typo in the "responding to events" tutorial (crosshairs must have been renamed to markers earlier, because at that point in the tutorial, no object with this name has been introduced).
basnijholt/holoviews,basnijholt/holoviews,ioam/holoviews,basnijholt/holoviews,ioam/holoviews,ioam/holoviews