Wrong colorscales YIOrRd and YIGnBu

[alexcjohnson]

We have an uppercase I in "YIOrRd" and "YIGnBu" - should be a lowercase L for yellow: "YlOrRd" or "YlGnBu".

At some point plotly.js had these typos in its built-in colorscales. We fixed that, and included a backward-compatibility fix that converts from I to l when used with Plotly.newPlot or Plotly.react, but it doesn't work with Plotly.restyle or Plotly.relayout (which I believe still get some use from plotly.py when editing an existing figure)

We should update the docs to only use the correct spelling.
Originally reported in plotly/plotly.js#4613