Hibernate Reactive Panache: improve error message

- when no current reactive session is found
- resolves quarkusio#36236

(cherry picked from commit 82c1323)

extensions/panache/hibernate-reactive-panache-common/runtime/src/main/java/io/quarkus/hibernate/reactive/panache/common/runtime/SessionOperations.java

@@ -161,8 +161,9 @@ public static Uni<Mutiny.Session> getSession() {
                 }
             } else {
                 throw new IllegalStateException("No current Mutiny.Session found"
-                        + "\n\t- no reactive session was found in the context and the context was not marked to open a new session lazily"
-                        + "\n\t- you might need to annotate the business method with @WithSession");
+                        + "\n\t- no reactive session was found in the Vert.x context and the context was not marked to open a new session lazily"
+                        + "\n\t- a session is opened automatically for JAX-RS resource methods annotated with an HTTP method (@GET, @POST, etc.); inherited annotations are not taken into account"
+                        + "\n\t- you may need to annotate the business method with @WithSession or @WithTransaction");
             }
         }
     }