Improve docs on transactionality of methods declared on repository interfaces.

We're now more specific on what CRUD methods means in the context of transactional query methods. Also, we now mention default methods explicitly in the discussion of query methods.

Fixes #2868.

Author: odrotbohm

Diff for: src/main/asciidoc/jpa.adoc

@@ -1120,7 +1120,7 @@ include::query-by-example.adoc[leveloffset=+1]
 [[transactions]]
 == Transactionality
 
-By default, CRUD methods on repository instances inherited from link:$$https://docs.spring.io/spring-data/data-jpa/docs/current/api/org/springframework/data/jpa/repository/support/SimpleJpaRepository.html$$[`SimpleJpaRepository`] are transactional.
+By default, methods inherited from `CrudRepository` inherited the transactional configuration from from link:$$https://docs.spring.io/spring-data/data-jpa/docs/current/api/org/springframework/data/jpa/repository/support/SimpleJpaRepository.html$$[`SimpleJpaRepository`].
 For read operations, the transaction configuration `readOnly` flag is set to `true`.
 All others are configured with a plain `@Transactional` so that default transaction configuration applies.
 Repository methods that are backed by transactional repository fragments inherit the transactional attributes from the actual fragment method.
@@ -1182,7 +1182,8 @@ Note that the call to `save` is not strictly necessary from a JPA point of view,
 [[transactional-query-methods]]
 === Transactional query methods
 
-To let your query methods be transactional, use `@Transactional` at the repository interface you define, as shown in the following example:
+Declared query methods (including default methods) do not get any transaction configuration applied by default.
+To run those methods transactionally, use `@Transactional` at the repository interface you define, as shown in the following example:
 
 .Using @Transactional at query methods
 ====