[HT] Added two parameters of the solid thermal expansion in the flow process

...s/HT/solid_thermal_expansion/i_solid_thermal_expansion.md

...ses/process/HT/solid_thermal_expansion/t_biot_constant.md

...process/HT/solid_thermal_expansion/t_thermal_expansion.md

ProcessLib/HT/CreateHTProcess.cpp

ProcessLib/HT/HTMaterialProperties.h