Missing references in the Get Started vignette and additional changes

The Riboust et al. (2019) reference should be added in the Get Started vignette for the CemaNeige function:

Riboust, P., G. Thirel, N. Le Moine and P. Ribstein (2019), Revisiting a simple degree-day model for integrating satellite data: implementation of SWE-SCA hystereses. Journal of Hydrology and Hydromechanics, doi: 10.2478/johh-2018-0004, 67, 1, 70–81.

PEdaily_Oudin should also be replaced by PE_Oudin

For the criteria section, maybe add a sentence saying that the calculation of composites of the criteria is also possible.