Update logging.xml

fix a typo
Merge pull request #250 from htynkn/patch-2

fix a typo in document of logging
Merge pull request #251 from wangdx/master

Improve the rest of configuration doc and one duplicated word in en doc.
Improve zh-doc, beginning of the Mapper.
Improve zh-doc, 'select' of Mapper.
Improve zh-doc, 'insert, update and delete' section of Mapper.