[10.0][csv2xml] Improvements in the documentation of csv2xml

[yaniaular]

Affected versions:

Odoo 10.0

Expected Behavior

• Update information about structure of csv folder
  • The __config__.py file in the folder csv is required. (Write about it in the README)
  • The folder to each csv file within csv folder
  • The column model and id in the csv file is required
  • Fix the tag to when it is __manifest__.py file
  • Should the company be required?