qapi: Clean up "Returns" sections

Drop list markup, since there's just one item left.

Drop "on success" where it is redundant with "Returns:".

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20240227113921.236097-7-armbru@redhat.com>

qapi/block-core.json

@@ -2457,7 +2457,7 @@
 # @unstable: This command is meant for debugging.
 #
 # Returns:
-#     - BlockDirtyBitmapSha256 on success
+#     BlockDirtyBitmapSha256
 #
 # Errors:
 #     - If @node is not a valid block device, DeviceNotFound
@@ -6084,7 +6084,7 @@
 # @name: optional the snapshot's name to be deleted
 #
 # Returns:
-#     - SnapshotInfo on success
+#     SnapshotInfo
 #
 # Errors:
 #     - If @device is not a valid block device, GenericError

qapi/machine.json

@@ -1090,7 +1090,7 @@
 # Return information about the balloon device.
 #
 # Returns:
-#     - @BalloonInfo on success
+#     @BalloonInfo
 #
 # Errors:
 #     - If the balloon driver is enabled but not functional because
@@ -1156,7 +1156,7 @@
 # message from the guest.
 #
 # Returns:
-#     - @HvBalloonInfo on success
+#     @HvBalloonInfo
 #
 # Errors:
 #     - If no hv-balloon device is present, guest memory status

qapi/misc.json

@@ -332,7 +332,7 @@
 # @opaque: A free-form string that can be used to describe the fd.
 #
 # Returns:
-#     - @AddfdInfo on success
+#     @AddfdInfo
 #
 # Errors:
 #     - If file descriptor was not received, GenericError