doc: fix wrong MySQL version

Reported by _so4. Thanks!!!

doc/locale/ja/LC_MESSAGES/news.po

@@ -8,7 +8,7 @@ msgstr ""
 "Project-Id-Version: groonga storage engine 1.0.1\n"
 "Report-Msgid-Bugs-To: \n"
 "POT-Creation-Date: 2014-07-28 16:09+0900\n"
-"PO-Revision-Date: 2014-07-28 16:37+0900\n"
+"PO-Revision-Date: 2014-08-04 22:09+0900\n"
 "Last-Translator: Kouhei Sutou <kou@clear-code.com>\n"
 "Language-Team: Japanese\n"
 "Language: ja\n"
@@ -56,9 +56,9 @@ msgid "Fixes"
 msgstr "修正"
 
 msgid ""
-"[rpm][centos] Built with MySQL 5.6.37 on CentOS. [Reported by YOSHIDA Mitsuo]"
+"[rpm][centos] Built with MySQL 5.5.37 on CentOS. [Reported by YOSHIDA Mitsuo]"
 msgstr ""
-"[rpm][centos] CentOSでMySQL 5.6.37でビルドするようにしました。[吉田さんが報"
+"[rpm][centos] CentOSでMySQL 5.5.37でビルドするようにしました。[吉田さんが報"
 "告]"
 
 msgid ""

doc/source/news.rst

@@ -25,7 +25,7 @@ Improvements
 Fixes
 ^^^^^
 
-* [rpm][centos] Built with MySQL 5.6.37 on CentOS.
+* [rpm][centos] Built with MySQL 5.5.37 on CentOS.
   [Reported by YOSHIDA Mitsuo]
 * Fixed to use lowercase for table name to avoid  lower/upper-case specific
   issue on Mac OS. [Patch by Toshihisa Tashiro]