include/rados/librados.h: fix documented rados_cluster_fsid return value

Signed-off-by: Lukas Stockner <[email protected]>

Author: Lukas Stockner

src/include/rados/librados.h

@@ -658,7 +658,7 @@ CEPH_RADOS_API int rados_cluster_stat(rados_t cluster,
  * @param cluster where to get the fsid
  * @param buf where to write the fsid
  * @param len the size of buf in bytes (should be 37)
- * @returns 0 on success, negative error code on failure
+ * @returns length of the string on success, negative error code on failure
  * @returns -ERANGE if the buffer is too short to contain the
  * fsid
  */