Update Lambda args without braces docs
Update Lambda args without braces docs

At least on the latest nightly (Scala 3.2.2-RC1-bin-20220910-ac6cd1c-NIGHTLY), the example without colons doesn't seem to work. Also, the `foldLeft` call seems to be missing the initial value.
sjrd/dotty,lampepfl/dotty,lampepfl/dotty,sjrd/dotty,dotty-staging/dotty,sjrd/dotty,lampepfl/dotty,dotty-staging/dotty,lampepfl/dotty,dotty-staging/dotty,lampepfl/dotty,dotty-staging/dotty,sjrd/dotty,dotty-staging/dotty,sjrd/dotty