Add spec for /scene-grids/
Add spec for /scene-grids/

Add SceneGrid object definition
Add examples for bbox parameters

raster-foundry/raster-foundry,aaronxsu/raster-foundry,azavea/raster-foundry,aaronxsu/raster-foundry,aaronxsu/raster-foundry,azavea/raster-foundry,azavea/raster-foundry,aaronxsu/raster-foundry,azavea/raster-foundry,raster-foundry/raster-foundry,azavea/raster-foundry,raster-foundry/raster-foundry