Improved documentation, group by

### BSON

- Added `BsonFieldWriter.write(String, BsonValueWriteable)` (f7e6b07a)

### DSL

- Added `$group`'s `_id` parameter (38bac2f8)
- `Path` is now `Comparable` (3ecec1e3)
- Added missing `Node` supertype of `CompoundNode` (5c9bb1f7)
- Cleaned up the `@DslMarker` annotation (!282)
- Fixed possible thread unsafety in `Node.freeze()` (#101, ca4f0011)

### Multiplatform

- Improved testing of the wire protocol (!279)

### Documentation

- Fixed broken links (!278)
- Improved documentation of the `dsl.tree` package (!285)
- Clarified the difference between `isIn` and `isOneOf` (#131, !283)

### Deployment

- This version has been tested against MongoDB 7.0.40