change doc string

[artur-pa]

Which issue(s) are closed by this pull request?

Error in the docstring: early_lateral_energy_fraction does not return a value in dB, but rather an energy ratio

  Returns
    -------
    Early Lateral Energy Fraction: numpy.ndarray
        Early lateral energy fraction (:math:`J_\mathrm{LF}`) in decibels,
        shaped according to the channel shape of the input EDCs.

Changes proposed in this pull request:

  Returns
    -------
    Early Lateral Energy Fraction: numpy.ndarray
        Early lateral energy fraction (:math:`J_\mathrm{LF}`),
        shaped according to the channel shape of the input EDCs.

[f-brinkmann]

Thanks for catching