Update McKinsey scatterplot

[xangregg]

A couple issues with the McKinsey scatterplot entry, "Pandemic End".

• It looks to be an imitation of an idea from NYT in Feb 2020. McKinsey does cite NYT as a source but only vaguely. I don't know if NYT has updated theirs like McKinsey has for new variants. So if it's worth keeping the McKinsey version, you might at least mention the NYT original in your notes.
• The McKinsey version includes zero on the log scale. The NYT version originally had that, too, but later removed it after realizing the error.