* fix link to documentation in the README.rst

* Update README.rst

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Co-authored-by: Viggo de Vries <viggo@highbiza.nl>

* project contribution section and code of conduct

* emails uploaded

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Co-authored-by: Brahim Chamakh <brahim.chamakh@medtech.tn>

There was a problem with the GitHub package link that was fixed

add django-oscar-zarinpal-gateway as 3rd party extention to README.srt

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

django-oscar-erp (or django-oscar_erp) bitbucket link doesn't exist anymore.

This reverts commit 9f547c2095.

Graciously contributed by Christoph Reimers at Byteyard.

As per [their blog post of the 27th April](https://blog.readthedocs.com/securing-subdomains/) ‘Securing subdomains’:

> Starting today, Read the Docs will start hosting projects from subdomains on the domain readthedocs.io, instead of on readthedocs.org. This change addresses some security concerns around site cookies while hosting user generated data on the same domain as our dashboard.

Test Plan: Manually visited all the links I’ve modified.

The demo site was not kept up to date with the recent changes in Oscar
due to time contraints. It should be moved to a separate demo repository
in the future.

Both sites are not available anymore: 

You can check their all url: 
* garmsby.co.uk (it's offline)
* www.fpsport.it  (was replaced with a static landing page)