Fix small typos throughout the documentation

[johangithub]

Found some typos while reading through, so I'm raising a PR here.

e.g., Ducklake works uses Parquet => Ducklake uses Parquet.

[johangithub]

I know that dangling comma is a feature, but not sure if the author intended it, so I included it here.

[szarnyasg]

Hi @johangithub – Thanks a lot for this PR! You caught a lot of subtle typos that slip through naive spell checking.

One day I'll print the PDF and read it in one go, because that allows for catching some more grammar issues/typos as well as some editing inconsistencies, but that's going to have to wait a bit :)

I know that dangling comma is a feature, but not sure if the author intended it, so I included it here.

Right. Indeed, the query would run successfully but I don't think it was the authors intention to leave the comma there.

Thanks again!