[playframework#713] Docs: document multiple required validation limit…

…ation

documentation/manual/validation.textile

@@ -84,7 +84,7 @@ This changes the output to:
 bc. name is required
 age is required
 
-p(note). *Limitation*: Play cannot determine the correct parameter name when more than required-field validation using the @validation.required(age)@ syntax fails. In this case, you must specify the field name: @validation.required("age", age)@.
+p(note). *Limitation*: Play cannot determine the correct parameter name when more than one required-field validation using the @validation.required(age)@ syntax fails. In this case, you must specify the field name directly, i.e. @validation.required("age", age)@.
 
 This error key defaults to the parameter name, and is itself used to look up a message. For example, the @name@ parameter in the @hello@ action method above could be localised with: