[FIX] doc: correct links to categories

Was pointing to a file that no longer exists

Fixes odoo/odoo#27741

closes odoo/odoo#27755

doc/howtos/backend/exercise-creation

@@ -22,7 +22,7 @@ Index: addons/openacademy/__manifest__.py
 +    'website': "http://www.yourcompany.com",
 +
 +    # Categories can be used to filter modules in modules listing
-+    # Check https://github.com/odoo/odoo/blob/master/odoo/addons/base/module/module_data.xml
++    # Check https://github.com/odoo/odoo/blob/12.0/odoo/addons/base/data/ir_module_category_data.xml
 +    # for the full list
 +    'category': 'Test',
 +    'version': '0.1',

doc/howtos/website/module-empty

@@ -31,7 +31,7 @@ new file mode 100644
 +    'website': "http://www.yourcompany.com",
 +
 +    # Categories can be used to filter modules in modules listing
-+    # Check https://github.com/odoo/odoo/blob/master/odoo/addons/base/module/module_data.xml
++    # Check https://github.com/odoo/odoo/blob/12.0/odoo/addons/base/data/ir_module_category_data.xml
 +    # for the full list
 +    'category': 'Uncategorized',
 +    'version': '0.1',

doc/reference/module.rst

@@ -130,4 +130,4 @@ Available manifest fields are:
 
 .. _semantic versioning: http://semver.org
 .. _existing categories:
-     https://github.com/odoo/odoo/blob/master/odoo/addons/base/module/module_data.xml
+     https://github.com/odoo/odoo/blob/12.0/odoo/addons/base/data/ir_module_category_data.xml

odoo/cli/templates/default/__manifest__.py.template

@@ -14,7 +14,7 @@
     'website': "http://www.yourcompany.com",
 
     # Categories can be used to filter modules in modules listing
-    # Check https://github.com/odoo/odoo/blob/master/odoo/addons/base/module/module_data.xml
+    # Check https://github.com/odoo/odoo/blob/12.0/odoo/addons/base/data/ir_module_category_data.xml
     # for the full list
     'category': 'Uncategorized',
     'version': '0.1',