In order for your ConfigEntry to be listed under your mod, it must meet this criteria:

1. The ConfigEntry is of type bool, int, or float
2. The field/property is static OR it's instanced under your entry class (EntryClass : BaseUnityPlugin)

If you've referenced an older version of this mod, the attribute is currently obselete and won't do anything.
The proper way to set up ranges can be done by using AcceptableValueRange when defining your config entry:

floatEntry = Config.Bind("General", "Float Entry", 2f, new ConfigDescription(null, new AcceptableValueRange<float>(2.5f, 10.5f)));
intEntry = Config.Bind("General", "Int Entry", 2, new ConfigDescription(null, new AcceptableValueRange<int>(0, 100)));