This commit improves the structure of the accounting documentation by
- reducing the levels necessary to reach the information
- grouping some docs
- moving content to their parent category page (content in all levels)
- renaming some sections to reflect the structure of the app better
task-3330093
closesodoo/documentation#4478
X-original-commit: 14afa1a1a2
Signed-off-by: Castillo Jonathan (jcs) <jcs@odoo.com>