man: add several future version info tags

(cherry picked from commit 85a1360)
(cherry picked from commit e6e0d813be1471a0c26c4f965ffdc3ad63cb3662)

Author: yuwata

man/version-info.xml

@@ -79,4 +79,7 @@
   <para id="v255">Added in version 255.</para>
   <para id="v256">Added in version 256.</para>
   <para id="v257">Added in version 257.</para>
+  <para id="v257">Added in version 258.</para>
+  <para id="v257">Added in version 259.</para>
+  <para id="v257">Added in version 260.</para>
 </refsect1>