Fix consistency of examples

[AnthonyMDev]

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

[Shane32]

Fine with me

[benjie]

This has turned from one compliance statement to two, both of which are "recommended". I don't think that's ideal - ideally we recommend that you "both refuse to execute the request and return a 400 status to say as much". Also now I come to think about it "fails to pass" is a bit redundant. Maybe something like:

Suggested change

	If a request fails to pass _GraphQL validation_, the server SHOULD NOT execute
	the request and SHOULD return 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.

[benjie]

NOTE: in traditional JSON we want two compliance statements here: should not execute, and SHOULD use 200, both of which are independent of each other (well... mostly. If you did execute then returning non-200 would be weird). You should always return 200, even on validation error; and you should not execute after validation error.

The same is not true with application/graphql-response+json - here the failure to execute and the 400 status are linked together. Failing to execute but returning non-4xx (e.g. 200) would be unexpected/undesired.

[martinbonnin]

Somewhat of a side question but since we're in the "examples" section here, shouldn't we "just" use regular verbs (not capitalized). Examples shouldn't really be normative?