Hugo 0.20.6

There have been some shouting on discuss.gohugo.io about some broken sites after the release of Hugo 0.20. This release reintroduces the old behaviour, making /my-blog-post/index.md work as expected.

Hugo now has:

• 16675+ stars
• 456+ contributors
• 156+ themes

Fixes  

• Avoid index.md in /index/index.html #3396
• Make missing GitInfo a WARNING b30ca4be @bep #3376
• Fix some of the fpm fields for deb 3bd1d057 @anthonyfok