Modernize contributing pages to align with current requirement of having an accepted ticket for non trivial changes

[Natalia Bidart]

Following some feedback from ​https://github.com/django/django/pull/17389, there are some parts in these docs:

​https://docs.djangoproject.com/en/dev/internals/contributing/bugs-and-features/
​https://docs.djangoproject.com/en/dev/internals/contributing/writing-code/submitting-patches/

that could benefit from being more explicit about the need to have an accepted ticket when working on non trivial changes.

Specifically, I think that this paragraph is misleading:

"As with most open-source projects, code talks. If you are willing to write the code for the feature yourself or, even better, if you’ve already written it, it’s much more likely to be accepted. Fork Django on GitHub, create a feature branch, and show us your work!"

And also the patch review checklist should explicitly mention that an accepted ticket is required to get reviews/discussion in a GH PR.

[Amir Karimi]

1. I think this paragraph "As with most open-source projects, code talks..." is kinda contradictory with what is stated above and can be deleted. I traced its Git history but didn't find out why it was added while there is a lot of emphasis on submitting tickets first.
2. Obviously, the patch review checklist requires reviews/discussion in its PR, but we can add it to the patch review checklist section.

[Maryam Yusuf]

I want to work on this. I have gone through the PR(​https://github.com/django/django/pull/17389) to see the feedback. Will assign it to myself and work on it.

[Sarah Boyce <42296566+sarahboyce@…>]

In 7e00fee3:

Fixed #35546 -- Emphasised accepted ticket requirement in contributing docs.