update api.rst

Author: wholmgren

docs/sphinx/source/api.rst

@@ -139,16 +139,16 @@ Decomposing and combining irradiance
    irradiance.poa_horizontal_ratio
    irradiance.beam_component
    irradiance.poa_components
-   irradiance.grounddiffuse
+   irradiance.get_poa_ground_diffuse
 
 Transposition models
 --------------------
 
 .. autosummary::
    :toctree: generated/
 
-   irradiance.total_irrad
-   irradiance.get_sky_diffuse
+   irradiance.get_total_poa_irradiance
+   irradiance.get_poa_sky_diffuse
    irradiance.isotropic
    irradiance.perez
    irradiance.haydavies