Post: deprecate old VCS support

[humitos]

Blog post to communicate our users about the deprecation of old VCS support:

• clear date on final removal
• clear brownout dates
• possible workarounds

Related https://github.com/readthedocs/readthedocs.org/issues/8840

Rendered version: https://read-the-docs-website--264.com.readthedocs.build/blog/2024/02/drop-support-for-subversion-mercurial-bazaar/

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📚 Documentation preview 📚: https://read-the-docs-website--264.com.readthedocs.build/

[humitos]

I chose this image for the blog post, https://unsplash.com/photos/wall-with-paints-f303VzauP6w. @ericholscher did you do everything manually to add the image to this repository for the newsletter? what size did you download it? how did you create the "credits" line? etc...

[humitos]

@ericholscher this is the process I followed for the Ruby post. Does it makes sense to you?

[agjohnson]

this is the process I followed for the Ruby post

That is what I would suggest for now too :+1:

[ericholscher]

@ericholscher this is the process I followed for the Ruby post. Does it makes sense to you?

Yea, pretty much 👍

[humitos]

This PR is ready for a final review.