Fix spelling

docs/async.md

@@ -2,7 +2,7 @@
 
 In some situations, you may wish to define asynchronous rules, for example when working with an external API. By default, FluentValidation allows custom rules defined with `MustAsync` or `CustomAsync` to be run asyhchronously, as well as defining asychronous coniditions with `WhenAsync`. 
 
-A simplistic solution that checks if a user ID is alrady in use using an external web API: 
+A simplistic solution that checks if a user ID is already in use using an external web API: 
 
 ```csharp
 public class CustomerValidator : AbstractValidator<Customer> {
@@ -31,4 +31,4 @@ var result = await validator.ValidateAsync(customer);
   If your validator contains asynchronous validators or asynchronous conditions, it's important that you *always* call `ValidateAsync` on your validator and never `Validate`. If you call `Validate`, then your asynchronous rules *will be run synchronously*, which is not desirable.
 
   You should not use asynchronous rules when `using automatic validation with ASP.NET <aspnet.html>`_ as ASP.NET's validation pipeline is not asynchronous. If you use asynchronous rules with ASP.NET's automatic validation, they will always be run synchronously. 
-```
+```