Add implementation descriptions to online help

[timspainNERSC]

While trying to rebase the branch issue127_thermo_demo, this block of code for the online help was removed. I don't think it works as intended, but the idea behind it, having a description of the implementations of a module, is a good one.

    map[pfx].push_back({ pfx + "." + Module<Nextsim::IAtmosphereBoundary>::moduleName(),
        ConfigType::MODULE, { CONSTANTATMOSPHEREBOUNDARY }, CONSTANTATMOSPHEREBOUNDARY, "",
        "A Module to provide atmospheric inputs to the model." });
    map[pfx].push_back({ pfx + "." + Module<Nextsim::IAtmosphereBoundary>::moduleName(),
        ConfigType::MODULE, { CONFIGUREDATMOSPHERE }, CONFIGUREDATMOSPHERE, "",
        "A configurable Module to provide atmospheric inputs to the model based on prescribed "
        "atmospheric state." });
    map[pfx].push_back({ pfx + "." + Module<Nextsim::IAtmosphereBoundary>::moduleName(),
        ConfigType::MODULE, { FLUXCONFIGUREDATMOSPHERE }, FLUXCONFIGUREDATMOSPHERE, "",
        "A configurable Module to provide atmospheric inputs to the model based on prescribed "
        "atmospheric fluxes." });
    map[pfx].push_back({ pfx + "." + Module<Nextsim::IAtmosphereBoundary>::moduleName(),
        ConfigType::MODULE, { MU71ATMOSPHERE }, MU71ATMOSPHERE, "",
        "A Module to provide atmospheric inputs to the model based on prescribed atmospheric "
        "fluxes according to Maykut and Untersteiner (1971)." });