Fix language in LightCurve.normalize() docstring
* lightcurve.py
(normalize): remove duplicate words in the function doc.
@@ -1025,7 +1025,7 @@ class LightCurve(QTimeSeries):
"""Returns a normalized version of the light curve.
The normalized light curve is obtained by dividing the ``flux`` and
- ``flux_err`` object attributes by the by the median flux.
+ ``flux_err`` object attributes by the median flux.
Optionally, the result will be multiplied by 1e2 (if `unit='percent'`),
1e3 (`unit='ppt'`), or 1e6 (`unit='ppm'`).
