Fix http link syntax in repeat.adoc

(cherry picked from commit cb8d045)

spring-batch-docs/modules/ROOT/pages/repeat.adoc

@@ -207,7 +207,7 @@ Java::
 The following example uses Java configuration to
 repeat a service call to a method called `processMessage` (for more detail on how to
 configure AOP interceptors, see the
-<<https://docs.spring.io/spring-framework/docs/current/reference/html/core.html#aop,Spring User Guide>>):
+https://docs.spring.io/spring-framework/docs/current/reference/html/core.html#aop[Spring User Guide]):
 +
 [source, java]
 ----
@@ -234,7 +234,7 @@ XML::
 The following example shows declarative iteration that uses the Spring AOP namespace to
 repeat a service call to a method called `processMessage` (for more detail on how to
 configure AOP interceptors, see the
-<<https://docs.spring.io/spring-framework/docs/current/reference/html/core.html#aop,Spring User Guide>>):
+https://docs.spring.io/spring-framework/docs/current/reference/html/core.html#aop[Spring User Guide]):
 +
 [source, xml]
 ----