Description of composite in filtering grammar.

It looks to me as though there is some commentary missing above the definition of composite at:

https://github.com/ButterCam/sisyphus/blob/f8d72b422f21ed718c778bc94dbe192e4892a405/lib/sisyphus-dsl/src/main/antlr/com/bybutter/sisyphus/dsl/filtering/grammar/Filter.g4#L135

