Correct wrong bool type to string in EFS static PV yaml

spec.csi.volumeAttributes are not allowed to configure the value with bool type, so correct it as string type in the yaml.
* Reference: https://issues.redhat.com/browse/OSDOCS-4490

Author: bysnupy

modules/persistent-storage-csi-efs-static-pv.adoc

@@ -37,7 +37,7 @@ spec:
     driver: efs.csi.aws.com
     volumeHandle: fs-ae66151a <2>
     volumeAttributes:
-        encryptInTransit: false <3>
+      encryptInTransit: "false" <3>
 ----
 <1> `spec.capacity` does not have any meaning and is ignored by the CSI driver. It is used only when binding to a PVC. Applications can store any amount of data to the volume.
 <2> `volumeHandle` must be the same ID as the EFS volume you created in AWS. If you are providing your own access point, `volumeHandle` should be ``<EFS volume ID>::<access point ID>``. For example: `fs-6e633ada::fsap-081a1d293f0004630`.