Update reference doc links to Spring Boot 3.3

[xenoterracide]

For example, I've seen a few more, not certain if they're hard coded or the version of spring boot is a parameter to a template

https://docs.spring.io/spring-graphql/reference/request-execution.html#execution.graphqlsource.schema-resources

this link refers to spring boot 3.2 instead of 3.3

looks for schema files

[bclozel]

This is now fixed in 1.3-SNAPSHOT docs, see https://docs.spring.io/spring-graphql/reference/1.3-SNAPSHOT/request-execution.html#execution.graphqlsource.schema-resources