Example correlation matrix

[machow]

Let's add a correlation matrix example to the docs (and / or a confusion matrix!)

Here's a confusion matrix from the pandas styler docs

[zaynpatel]

Hi @machow - I am happy to work on adding this example to the docs. In the pandas styler docs example you shared they build everything with CSS/specific pandas table styles. Is the goal for this issue to use same data as the styler docs example but recreate the table using great-tables?