Add --help to wcli.sh about walletwasabi HOT 3 OPEN

--- a/WalletWasabi/Rpc/JsonRpcRequestHandler.cs
+++ b/WalletWasabi/Rpc/JsonRpcRequestHandler.cs
@@ -81,6 +81,11 @@ public class JsonRpcRequestHandler<TService>
     {
         var methodName = jsonRpcRequest.Method;
 
+        if (methodName == "help")
+        {
+            return ServiceMetadata(jsonRpcRequest.Id).ToJson(DefaultSettings);
+        }
+
         if (!MetadataProvider.TryGetMetadata(methodName, out var procedureMetadata))
         {
             return Error(JsonRpcErrorCodes.MethodNotFound, $"'{methodName}' method not found.", jsonRpcRequest.Id);
@@ -182,6 +187,24 @@ public class JsonRpcRequestHandler<TService>
         }
     }
 
+    private JsonRpcResponse ServiceMetadata(string requestId) =>
+        JsonRpcResponse.CreateResultResponse(
+            requestId,
+            MetadataProvider.EnumerateServiceInfo()
+                .Select(
+                    x => new
+                    {
+                        name = x.Name,
+                        parameters = x.Parameters.Select(
+                            p => new
+                            {
+                                name = p.name,
+                                type = p.type.Name.ToLower(),
+                                optional = p.isOptional,
+                                defaultValue = p.defaultValue
+                            })
+                    }));
+
     private string Error(JsonRpcErrorCodes code, string reason, string id)
     {
         var response = JsonRpcResponse.CreateErrorResponse(id, code, reason);