doc: update "upgrade sequence"

doc/source/news.rst

@@ -16,40 +16,45 @@ Release 2.05 - 2012/07/29
    in :doc:`/userguide/storage`, please recreate (dump and restore)
    database.
 
-Here are upgrade sequence.
+Here is upgrade sequence.
 
-We dump a database that uses mroonga::
+Dump a database that uses mroonga::
 
   % mysqldump MY_MROONGA_DATABASE > database-mroonga.dump
 
-We drop the existing database::
+Drop the existing database::
 
   % mysql -u root -e 'DROP DATABASE MY_MROONGA_DATABASE'
 
-We upgrade to "mroonga" storage engine. We will use
+You must upgrade to "mroonga" storage engine. Use
 ``apt-get`` on Debian GNU/Linux or Ubuntu and ``yum`` on
 CentOS or Fedora.
 
 apt-get::
 
   % sudo apt-get install -y mysql-server-mroonga
 
-yum::
+yum (upgrade from mroonga release prior to v2.02)::
 
   % sudo yum remove -y mysql-mroonga
   % sudo yum install -y mysql-mroonga
 
+yum (upgrade from mroonga release v2.03 or later)::
+
+  % sudo yum install -y mysql-mroonga
+
 .. caution::
 
-   We don't forget to run ``yum remove`` before ``yum
-   install``. If we forget to run ``yum remove``, we will break
+   Don't forget to run ``yum remove`` before ``yum
+   install`` if you upgrade mroonga prior to v2.02 release.
+   If we forget to run ``yum remove``, we will break
    a MySQL's system table.
 
-We recreate a database::
+Recreate a database::
 
   % mysql -u root -e 'CREATE DATABASE MY_MROONGA_DATABASE'
 
-We restore a database by modified dump file::
+Restore a database by modified dump file::
 
   % mysql -u root MY_MROONGA_DATABASE < database-mroonga.dump