mkEnableOption already adds "Whether to enable" and ends with a ".", so remove that duplication from the help text. Also reword it slightly while at it. (cherry picked from commit 5d3dca497ba7d20c662e8144c0bedb69433a9e4a)
Fixes error: The option value `meta.maintainers' in `nixos/modules/programs/hamster.nix' is not of type `list of maintainers'.