Rename basic21 to reflect actual purpose

Change-Id: I144bb7e1f516e6671e1ea9dcee7054bf4dabccc3
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/robot-systest/testsuite/basic_21-persistent_volumes.robot b/robot-systest/testsuite/basic_21-support_of_volumes.robot
similarity index 100%
rename from robot-systest/testsuite/basic_21-persistent_volumes.robot
rename to robot-systest/testsuite/basic_21-support_of_volumes.robot