qapi: Fix mangled "Returns" sections in documentation

Commit e050e42 (qapi: Use explicit bulleted lists) added list
markup to correct bad rendering:

    A JSON block comment like this:
         Returns: nothing on success
                  If @node is not a valid block device, DeviceNotFound
                  If @name is not found, GenericError with an explanation

    renders like this:

         Returns: nothing on success If node is not a valid block device,
         DeviceNotFound If name is not found, GenericError with an explanation

    because whitespace is not significant.

    Use an actual bulleted list, so that the formatting is correct.

It missed a few instances.  Commit a937b6a (qapi: Reformat doc
comments to conform to current conventions) then reflowed them.

Revert the reflowing, and add list markup.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20240120095327.666239-6-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

qapi/net.json

@@ -18,8 +18,9 @@
 #
 # @up: true to set the link status to be up
 #
-# Returns: Nothing on success If @name is not a valid network device,
-#     DeviceNotFound
+# Returns:
+#     - Nothing on success
+#     - If @name is not a valid network device, DeviceNotFound
 #
 # Since: 0.14
 #
@@ -44,8 +45,9 @@
 #
 # Since: 0.14
 #
-# Returns: Nothing on success If @type is not a valid network backend,
-#     DeviceNotFound
+# Returns:
+#     - Nothing on success
+#     - If @type is not a valid network backend, DeviceNotFound
 #
 # Example:
 #
@@ -64,8 +66,9 @@
 #
 # @id: the name of the network backend to remove
 #
-# Returns: Nothing on success If @id is not a valid network backend,
-#     DeviceNotFound
+# Returns:
+#     - Nothing on success
+#     - If @id is not a valid network backend, DeviceNotFound
 #
 # Since: 0.14
 #

qapi/qdev.json

@@ -89,8 +89,9 @@
 #
 # @id: the device's ID or QOM path
 #
-# Returns: Nothing on success If @id is not a valid device,
-#     DeviceNotFound
+# Returns:
+#     - Nothing on success
+#     - If @id is not a valid device, DeviceNotFound
 #
 # Notes: When this command completes, the device may not be removed
 #     from the guest.  Hot removal is an operation that requires guest

qapi/qom.json

@@ -1056,8 +1056,9 @@
 #
 # Create a QOM object.
 #
-# Returns: Nothing on success Error if @qom-type is not a valid class
-#     name
+# Returns:
+#     - Nothing on success
+#     - Error if @qom-type is not a valid class name
 #
 # Since: 2.0
 #
@@ -1078,8 +1079,9 @@
 #
 # @id: the name of the QOM object to remove
 #
-# Returns: Nothing on success Error if @id is not a valid id for a QOM
-#     object
+# Returns:
+#     - Nothing on success
+#     - Error if @id is not a valid id for a QOM object
 #
 # Since: 2.0
 #