Deploy CircleCi build to Netlify

[wilzbach]

Needs to be a branch at upstream to be able to test the upload. Remaining steps for further work:

• [ ] kindle
• [ ] latex
• [ ] prerelease
• [ ] translate all .htaccess to Netlify rewrites

Preview: https://dlang.netlify.com

[dlang-bot]

Thanks for your pull request, @wilzbach!

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