Fix consistency of examples (#332)

* Fix consistency of examples

Fix the Document Validation Failure examples to match the wording of the other examples.

* Update GraphQLOverHTTP.md

* Update spec/GraphQLOverHTTP.md

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Co-authored-by: Benjie <[email protected]>

Author: AnthonyMDev

spec/GraphQLOverHTTP.md

@@ -600,7 +600,7 @@ code `200` (Okay).
 
 ##### Document validation failure
 
-Requests that fail to pass _GraphQL validation_, the server SHOULD NOT execute
+If a request fails to pass _GraphQL validation_, the server SHOULD NOT execute
 the request and SHOULD return a status code of `200` (Okay).
 
 ##### Operation cannot be determined
@@ -722,8 +722,8 @@ code `400` (Bad Request).
 
 ##### Document validation failure
 
-Requests that fail to pass _GraphQL validation_ SHOULD be denied execution with
-a status code of `400` (Bad Request).
+If a request fails _GraphQL validation_, the server SHOULD return a status code
+of `400` (Bad Request) without proceeding to GraphQL execution.
 
 ##### Operation cannot be determined