Move CONTRIBUTING.md to documentation site

[AetherUnbound]

Description

Our current contributing guide exists locally in the repository: https://github.com/WordPress/openverse/blob/523a3599c34463275ce57c4e4ce6c14de1baefbd/CONTRIBUTING.md

It would be ideal to move this into the documentation site at docs.openverse.org, where most of our other quickstart/contributor information exists!

Note: When we convert this into Sphinx, we should also emphasize further the verbiage about choosing more than one good first issue - https://github.com/WordPress/openverse/blob/209cd44abed611ae4a2ef97ea77e8d2b0b612a53/CONTRIBUTING.md#friendly-notes (we've had a few folks ask about this, so it seems useful to highlight it better).

This would involve moving the file from it's current position into documentation/general, adding a callout for the above using a MyST callout, and then linking from the current CONTRIBUTING.md to the new location on the docs site.

[shivamganwani]

@AetherUnbound I'd like to pick this up

[zackkrida]

Thanks, @shivamganwani! Please just ping @WordPress/openverse-maintainers here if you have any questions 😄

[shivamganwani]

@WordPress/openverse-maintainers
I think I found an issue, not sure.
In the Contributing section of the Readme there is this line See the [CONTRIBUTING.md](https://github.com/WordPress/openverse/blob/main/CONTRIBUTING.md) file for details.

Now I click on the link and it takes me to contributing guidelines page. All good till now.
Now I scroll down and there is a part where the below links are present

[GitHub contribution practices](https://docs.openverse.org/reference/github_contribution_practices.html)
[Dev flow](https://docs.openverse.org/reference/dev_flow.html)
[General setup guide](https://docs.openverse.org/guides/general_setup.html)
[Quickstart guide](https://docs.openverse.org/guides/quickstart.html)

Here comes the issue, all these links take me to 404 Not found. Can someone explain if this is really an issue or am I doing something wrong.

[AetherUnbound]

Ah, great find @shivamganwani! We recently restructured our documentation (#1846) and that probably caused all those links to break. Here are the new ones:

[GitHub contribution practices](https://docs.openverse.org/meta/github_contribution_practices.html)
[Dev flow](https://docs.openverse.org/meta/dev_flow.html)
[General setup guide](https://docs.openverse.org/general/general_setup.html)
[Quickstart guide](https://docs.openverse.org/general/quickstart.html)

[shivamganwani]

@AetherUnbound so we're making a separate ticket or fixing this in this one?

[AetherUnbound]

Do you mind including that in your changes in #2030? 😄

[shivamganwani]

Not at all @AetherUnbound