cli: add missing newlines in usage

[bradh]

Fixes this problem in the CLI usage:

      --(no-)combine-intra-cus: Whether the encoder tries to code a cu
                                   on lower depth even when search is not
                                   performed on said depth. Should only
                                   be disabled if cus absolutely must not
                                   be larger than limited by the search.
                                   [enabled]      --force-inter          : Force the encoder to use inter always.
                               This is mostly for debugging and is not
                               guaranteed to produce sensible bitstream or
                               work at all. [disabled]      --tr-depth-intra <int> : Transform split depth for intra blocks [0]
      --(no-)bipred          : Bi-prediction [disabled]

Also corrects a marginally-long line in the usage output

[fador]

Thank you!