Document batch resizing

[Delaunay]

size     : int  = getenv("MILABENCH_SIZER_BATCH_SIZE", int)     # Override the batch size
autoscale: bool = getenv("MILABENCH_SIZER_AUTO", False)         # Enable autoscaling from the GPU max memory
multiple : int  = getenv("MILABENCH_SIZER_MULTIPLE", int)       # Force the Batch size to be a multiple of something
optimized: bool = getenv("MILABENCH_SIZER_OPTIMIZED", int)      # Use configured batch
capacity : str  = getenv("MILABENCH_SIZER_CAPACITY", str)       # Override GPU max memory