TLDR pages: Simplified and community-driven man pages

For more, see

* https://news.ycombinator.com/item?id=7166257

* https://news.ycombinator.com/item?id=7308852

* https://news.ycombinator.com/item?id=10797303

* https://news.ycombinator.com/item?id=14985449

* https://news.ycombinator.com/item?id=13071636