Docstring fixes for var3d (remove extra items) and etkf (typo)

Author: kysolvik

dabench/dacycler/_etkf.py

@@ -104,7 +104,7 @@ def _compute_analysis(self,
         Args:
           Xb: Forecast/background ensemble with shape
             (system_dim, ensemble_dim).
-          Y: Observation array with shape (obs_time_time, observation_dim)
+          Y: Observation array with shape (obs_time_dim, observation_dim)
           H: Linear observation operator with shape (observation_dim,
             system_dim).
           h: Callable observation operator (optional).

dabench/dacycler/_var3d.py

@@ -22,10 +22,6 @@ class Var3D(dacycler.DACycler):
         system_dim: System dimension.
         delta_t: The timestep of the model (assumed uniform)
         model_obj: Forecast model object.
-        in_4d: True for 4D data assimilation techniques (e.g. 4DVar).
-            Always False for Var3D.
-        ensemble: True for ensemble-based data assimilation techniques
-            (ETKF). Always False for Var3D
         B: Initial / static background error covariance. Shape:
             (system_dim, system_dim). If not provided, will be calculated
             automatically.