Update 1_2_Guided_Tour_install_functionality.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_install_functionality.rst#i18n/zh_hans/source/book/1/1_2_Guided_Tour/1_2_Guided_Tour_install_functionality.rst