Added instructions to add custom product attributes to Solr index and OSCAR_SEARCH_FACETS

There are small typos in:
- docs/source/releases/v0.5.rst
- docs/source/releases/v3.2.rst
- src/oscar/apps/offer/queryset.py
- tests/integration/basket/test_models.py

Fixes:
- Should read `threshold` rather than `treshold`.
- Should read `overridden` rather than `overidden`.
- Should read `category` rather than `catagory`.
- Should read `applications` rather than `appliations`.

Signed-off-by: Tim Gates <tim.gates@iress.com>

Signed-off-by: Tim Gates <tim.gates@iress.com>

Co-authored-by: Viggodevries <viggo@highbiza.nl>

* Implement shareable wishlists.

* Raise permission denied 403 instead of 404 if a user has no access to the wishlist.

* Change translation messages

* Implemented predefined product options

* css

* added missing migration in the test app

* Added tests

* added test

* added test

* Added more testz

* Added validation

* Renamed add_optional_choice to add_empty_choice

* added release notes

* Added help_text help text.

yup

* Use a JSONField for the option value

* removed pylint

* fix display of multi and checkbox in basket and order (#13)

* fix display of multi and checkbox in basket and order

Co-authored-by: willeke huizing <38961397+willekeh@users.noreply.github.com>

The attribute wasn’t persisted to database because the save() method was
not called. This was inconsistent with other fields.

Fixes #3767.

- Remove deprecated features and update deprecation notices for next
release.
- Update release notes.
- Bump version

- allow creation of offers of all types
- allow creation of vouchers with multiple offers
- allow creation of voucher sets of all usages, and with multiple offers

Also:
- change the default value of the "target_path" argument
- improve documentation of the "target_path" argument
- fix old documentation that says frontend and dashboard use different
  Bootstrap versions

`make css` has been renamed to `make assets`.

I struggled with migrations when upgrading from Oscar 2.0.4 to 2.1.
@solarissmoke kindly helped out, and I want to say thank you by adding
the bits I learned to the docs.

Where an initial value is required, this should be set on the form field
itself.

Fixes #3590.

Fixes #3517.

Co-authored-by: Basil Dubyk <samitnuk.work@gmail.com>
Co-authored-by: Alexander Gaevsky <sasha@sasha0.ru>
Co-authored-by: Joseph Wayodi <jwayodi@gmail.com>

Fixes #3258.

Non-exclusive offers that only allow combination with specific other offers

Also remove unused migrations test for MySQL.