treewide: streamline 'extraConfig' descriptions

modules/bitcoind.nix

@@ -90,7 +90,7 @@ in {
           par=16
           logips=1
         '';
-        description = "Additional configurations to be appended to <filename>bitcoin.conf</filename>.";
+        description = "Extra lines appended to <filename>bitcoin.conf</filename>.";
       };
       dataDir = mkOption {
         type = types.path;

modules/clightning.nix

@@ -67,7 +67,7 @@ in {
     extraConfig = mkOption {
       type = types.lines;
       default = "";
-      description = "Additional lines appended to the config file.";
+      description = "Extra lines appended to the configuration file.";
     };
     user = mkOption {
       type = types.str;

modules/liquid.nix

@@ -87,9 +87,8 @@ in {
           par=16
           rpcthreads=16
           logips=1
-
         '';
-        description = "Additional configurations to be appended to <filename>elements.conf</filename>.";
+        description = "Extra lines appended to <filename>elements.conf</filename>.";
       };
       dataDir = mkOption {
         type = types.path;

modules/lnd.nix

@@ -118,7 +118,7 @@ in {
       example = ''
         autopilot.active=1
       '';
-      description = "Additional configurations to be appended to <filename>lnd.conf</filename>.";
+      description = "Extra lines appended to <filename>lnd.conf</filename>.";
     };
     package = mkOption {
       type = types.package;