Typo in horizon shading gallery example

[williamhobbs]

Describe the bug
In the horizon shading gallery example, there appears to be a typo. This sentence should read, "when solar elevation is less than...".

pvlib-python/docs/examples/shading/plot_simple_irradiance_adjustment_for_horizon_shading.py

Lines 17 to 18 in 6b9476b

	# series data. Finally, in times when solar elevation is greater than the
	# interpolated horizon elevation angle, DNI is set to 0.