[Documentation] Warning instead of code

[raffaem]

Hello,

thanks very much for this package.

In reading the documentation, I noticed that in this example it says:

Warning: package 'ggplot2' was built under R version 4.2.3

instead of the code needed to plot the below plot.

[lrberge]

Thanks! I'll remove the ugly warning in the next release. BTW the code to generate the plot is not intended to be displayed in the document, but you can find it here: https://github.com/lrberge/fixest/blob/206661df3b709d1eddd8eaac6b6c1f8496a29934/vignettes/fixest_walkthrough.Rmd#L629