Added Sphinx docs

See merge request Jan.Habscheid/bsc-electrolytemodels!1

E-Diode working, problem was missing solvation + Solvation for DLKap bcs. of verification with Fuhrmann included

DLKap Update for compressible case, solvatin not working, as y_n not coming from expressions for y_alpha

E-Diode not working, concentrations seem to be uncouupled, fixed 1/Lambda2 in Var.Form and found out, that Lambda2 and a2 also determine maximum of the concentrations at Neumann Cond

Added Electrolytic Diode, but only working for Potential (pressure), rectification effect from Fuhrmann_Entropy paper cannot be observed in fractions