Stop referring to JDO and outdated JDBC versions in documentation

Closes gh-31183

spring-tx/src/main/java/org/springframework/transaction/SavepointManager.java

@@ -25,7 +25,7 @@ package org.springframework.transaction;
  * Just use this programmatic savepoint handling for advanced needs;
  * else, a subtransaction with PROPAGATION_NESTED is preferable.
  *
- * <p>This interface is inspired by JDBC 3.0's Savepoint mechanism
+ * <p>This interface is inspired by JDBC's Savepoint mechanism
  * but is independent of any specific persistence technology.
  *
  * @author Juergen Hoeller

spring-tx/src/main/java/org/springframework/transaction/TransactionDefinition.java

@@ -125,7 +125,7 @@ public interface TransactionDefinition {
 	 * <p><b>NOTE:</b> Actual creation of a nested transaction will only work on
 	 * specific transaction managers. Out of the box, this only applies to the JDBC
 	 * {@link org.springframework.jdbc.datasource.DataSourceTransactionManager}
-	 * when working on a JDBC 3.0 driver. Some JTA providers might support
+	 * when working on a JDBC 3.0+ driver. Some JTA providers might support
 	 * nested transactions as well.
 	 * @see org.springframework.jdbc.datasource.DataSourceTransactionManager
 	 */

spring-tx/src/main/java/org/springframework/transaction/support/AbstractPlatformTransactionManager.java

@@ -469,7 +469,7 @@ public abstract class AbstractPlatformTransactionManager
 			if (useSavepointForNestedTransaction()) {
 				// Create savepoint within existing Spring-managed transaction,
 				// through the SavepointManager API implemented by TransactionStatus.
-				// Usually uses JDBC 3.0 savepoints. Never activates Spring synchronization.
+				// Usually uses JDBC savepoints. Never activates Spring synchronization.
 				DefaultTransactionStatus status = newTransactionStatus(
 						definition, transaction, false, false, true, debugEnabled, null);
 				this.transactionExecutionListeners.forEach(listener -> listener.beforeBegin(status));