Correct comment about SWIFT_LOOPBACK_DISK_SIZE.

The comment regarding SWIFT_LOOPBACK_DISK_SIZE in lib/swift used the
incorrect unit (bytes instead of kilobytes).

Change-Id: I86117e36141c0a028a6fa6878a4d540f624e759d
diff --git a/lib/swift b/lib/swift
index c433387..b418eda 100644
--- a/lib/swift
+++ b/lib/swift
@@ -39,7 +39,8 @@
 SWIFT_CONFIG_DIR=${SWIFT_CONFIG_DIR:-/etc/swift}
 
 # DevStack will create a loop-back disk formatted as XFS to store the
-# swift data. Set ``SWIFT_LOOPBACK_DISK_SIZE`` to the disk size in bytes.
+# swift data. Set ``SWIFT_LOOPBACK_DISK_SIZE`` to the disk size in
+# kilobytes.
 # Default is 1 gigabyte.
 SWIFT_LOOPBACK_DISK_SIZE=${SWIFT_LOOPBACK_DISK_SIZE:-1000000}