Correct misspelled class name

docs/api-guide/validators.md

@@ -100,7 +100,7 @@ The validator should be applied to *serializer classes*, like so:
 
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-**Note**: The `UniqueTogetherValidation` class always imposes an implicit constraint that all the fields it applies to are always treated as required. Fields with `default` values are an exception to this as they always supply a value even when omitted from user input.
+**Note**: The `UniqueTogetherValidator` class always imposes an implicit constraint that all the fields it applies to are always treated as required. Fields with `default` values are an exception to this as they always supply a value even when omitted from user input.
 
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