Missed time unit in package.ent (chapter06/autoconf)

packages.ent

@@ -29,7 +29,7 @@
 <!ENTITY autoconf-home "&gnu-software;autoconf/">
 <!ENTITY autoconf-ch6-du "17.3 MB">
 <!ENTITY autoconf-ch6-sbu-tests "3.2">
-<!ENTITY autoconf-ch6-sbu "不到 0.1 SBU (测试需要约 &autoconf-ch6-sbu-tests;)">
+<!ENTITY autoconf-ch6-sbu "不到 0.1 SBU (测试需要约 &autoconf-ch6-sbu-tests; SBU)">
 
 <!ENTITY automake-version "1.15.1">
 <!ENTITY am-minor-version "1.15">