Rewrite github-proxy.com to github.com

[adamziel]

Playground now has a direct support for cloning Git repositories and @stoph asked if it's okay to shut down github-proxy.com. The only technical blocker is a bunch of existing Blueprints still referencing the github-proxy.com domain. To keep them working, let's internally rewrite any references to github-proxy.com with corresponding git references. We already do something similar for rewriting github.com URLs to raw.githubusercontent.com URLs.

[fellyph]

I have found references from GitHub proxy at:

• https://wordpress.github.io/wordpress-playground/guides/for-plugin-developers
• https://wordpress.github.io/wordpress-playground/guides/for-theme-developers

[adamziel]

Wow, thank you for proactively looking these up @fellyph 🎉

[fellyph]

Do you think we should remove those references and update them to point to the new URLs?

[adamziel]

Yes - and the updated Blueprint won't reference a URL but a git resource.