part: correct documentation of part_get_bootable()

We have to use 'Return:' to render the description of the return value in
the HTML documentation.

Fixes: f55aa4454ac3 ("part: Add a fallback for part_get_bootable()")
Fixes: dcffa4428d03 ("part: Add a function to find the first bootable partition")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/include/part.h b/include/part.h
index db34bc6..32ee404 100644
--- a/include/part.h
+++ b/include/part.h
@@ -685,8 +685,8 @@
 /**
  * part_get_bootable() - Find the first bootable partition
  *
- * @desc: Block-device descriptor
- * @return first bootable partition, or 0 if there is none
+ * @desc:	Block-device descriptor
+ * Return:	first bootable partition, or 0 if there is none
  */
 int part_get_bootable(struct blk_desc *desc);