update ChangeLog

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@27261 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,7 @@
+Thu Apr  8 14:33:24 2010  URABE Shyouhei  <shyouhei@ruby-lang.org>
+
+	* configure.in: --disable-install-doc should prohibit doxygen.
+
 Thu Apr  8 14:23:51 2010  NAKAMURA Usaku  <usa@ruby-lang.org>
 
 	* include/ruby/win32.h: include errno.h before defining errnos.