minor fixes

- bitcoind: Remove obsolete defaultText
- clightning: Fix description
  Option `address` can't be used to specify a socket path because it's
  used explicitly as an IP address in many places.
- lnd: Break up overlong line
  This is required by commit `services: support 0.0.0.0/:: in `address` options`
- nix-bitcoin.nix: Formatting
- secrets: Improve descriptions

modules/clightning.nix

@@ -7,7 +7,7 @@ let
     address = mkOption {
       type = types.str;
       default = "127.0.0.1";
-      description = "IP address or UNIX domain socket to listen for peer connections.";
+      description = "Address to listen for peer connections.";
     };
     port = mkOption {
       type = types.port;