Correct some module docstrings

lisainstrument/fixed_shift_dask.py

-"""Functions for applying dynamic real-valued shifts to dask arrays using Lagrange interpolation
+"""Functions for applying fixed real-valued shifts to dask arrays using Lagrange interpolation
 
-Use make_dynamic_shift_lagrange_dask to create a Lagrange interpolator for dask arrays.
+Use make_fixed_shift_lagrange_dask to create a Lagrange interpolator for dask arrays.
 """
 
 from __future__ import annotations

lisainstrument/fixed_shift_numpy.py

-"""Functions for interpolating numpy arrays with 1D  regularly spaced data
+"""Functions for applying fixed real-valued shifts to numpy arrays using Lagrange interpolation
 
-This provides a generic interface RegularInterpolator as well as two interpolation
-methods, linear and Lagrange. The latter is written from scratch, see module
-regular_interpolator_dsp for another one based on the dsp.timeshift Lagrange interpolator.
+This provides a generic interface FixedShiftCore as well as an implementation using
+Lagrange interpolation. The latter is written from scratch, see module
+fixed_shift_dsp for another one based on the dsp.timeshift Lagrange interpolator.
 """
 
 from __future__ import annotations