docopt : Command-line interface description language
how2 : stackoverflow from the terminal.
how2 finds the simplest way to do something in a unix shell. It's like man, but you can query it in natural language.
ADR Tools : A command-line tool for working with Architecture Decision Records (ADRs).
HTTP API design : This guide describes a set of HTTP+JSON API design practices, originally extracted from work on the Heroku Platform API.
Code Maat : Code Maat is a command line tool used to mine and analyze data from version-control systems (VCS).
The TLDR pages are a community effort to simplify the beloved man pages with practical examples.