Unindent before `)`

Currently the indentation rule for M2-mode (which is the de factor standard M2 style) is like this:
```m2
f = x -> (
    2 * x
    )
```
More and more though, as people use VSCode or learn M2 after other languages, they expect something like:
```m2
f = x -> (
    2 * x
)
```
I think we should discuss making this official in M2-mode so there isn't two different styles floating around.