`[]` should be `{}` in "Where did my brackets go" section

[jerlich]

Cool package. When reading the docs, I noticed a [] that should have been updated to a {}

https://github.com/FedeClaudi/Term.jl/blob/094339bc1a41a73296cec54c2a36dc3c52457076/docs/src/basics/styled_text.md?plain=1#L89C211-L89C216