Add deprecation warning for irradiance.king

pvlib/irradiance.py

@@ -989,6 +989,12 @@ def reindl(surface_tilt, surface_azimuth, dhi, dni, ghi, dni_extra,
     return sky_diffuse
 
 
+@deprecated(
+    since="0.15.2",
+    removal="",
+    name="pvlib.irradiance.king",
+    alternative="other diffuse transposition models in pvlib.irradiance",
+)
 def king(surface_tilt, dhi, ghi, solar_zenith):
     '''
     Determine diffuse irradiance from the sky on a tilted surface using