Documentation: Add note to irradiance.haydavies docstring. Close #1352 (#1353)

* PR for issue #1314

* Documentation: Added note to `irradiance.haydavies` docstring. Close #1352

Added a note about projection_ratio parameter to `irradiance.haydavies` docstring as mentioned by @kanderso-nrel .

* Documentation: Add note to irradiance.haydavies docstring. Update #1353

Added the changes suggested by @kanderso-nrel

Co-authored-by: Kevin Anderson <[email protected]>

Co-authored-by: Kevin Anderson <[email protected]>

Author: Carlosbogo

pvlib/irradiance.py

@@ -795,6 +795,12 @@ def haydavies(surface_tilt, surface_azimuth, dhi, dni, dni_extra,
     sky_diffuse : numeric
         The sky diffuse component of the solar radiation.
 
+    Notes
+    ------
+    When supplying ``projection_ratio``, consider constraining its values
+    when zenith angle approaches 90 degrees or angle of incidence
+    projection is negative. See code for details.
+
     References
     -----------
     .. [1] Loutzenhiser P.G. et. al. "Empirical validation of models to