Small fixes needed to tutorial part 2

[magnushammar]

I found some issues with the documentation that might be a stumbling block for a F# beginner. This might not be the right forum to contribute to docs, but I start here :)

Fixes can be seen here, tested with .Net 5 and 6
https://gist.github.com/magnushammar/50ca4adf881f8506ee43db80144e5b1e/revisions

Edit: Missed that fst and snd needed to swap place for the chart to render as shown.
https://gist.github.com/magnushammar/50ca4adf881f8506ee43db80144e5b1e#file-app-fsx-L25