Add docs link to Concepts.html#ConstantCombinatorParameters

[sparr]

http://lua-api.factorio.com/latest/LuaC ... avior.html has links to http://lua-api.factorio.com/latest/Conc ... Parameters and #DeciderCombinatorParameters but is missing links in the equivalent places for #ConstantCombinatorParameters. This made it confusingly difficult to figure out what goes in that parameters table.