Update 1_2_Guided_Tour_openerp.rst

Fixed ref : 
http://bazaar.launchpad.net/~openerp-community/openobject-doc/6.1/revision/1869/i18n/zh_hans/source/book/1/1_2_Guided_Tour/1_2_Guided_Tour_openerp.rst#i18n/zh_hans/source/book/1/1_2_Guided_Tour/1_2_Guided_Tour_openerp.rst