Example using the d3.ringNote
plugin to add circle annotations to a chart. Drag the dashed circles and
the text to move the annotation elements. These moveable,
dashed-line circles will disappear if ringNote.draggable(false) is called.
The chart shows the eruption duration and waiting time between eruptions
for the Old Faithful geyser in Yellowstone National Park. This is
from the datasets
R package.