Documentation

Documentation is any communicable material that is used to describe, explain or instruct regarding some attributes of an object, system or procedure, such as its parts, assembly, installation, maintenance and use. As a form of knowledge management and knowledge organization, documentation can be provided on paper, online, or on digital or analog media, such as audio tape or CDs. Examples are user guides, white papers, online help, and quick-reference guides. Paper or hard-copy documentation has become less common. Documentation is often distributed via websites, software products, and other online applications.
— Wikipedia

I use dasht to search through offline dash documentation files.

For Unix commands and programs documentation I’m using man and tldr (community-driven man pages client) programs.

Man usage: man [OPTION...] [SECTION] PAGE...

Tldr usage: tldr [OPTIONS] [COMMAND]..., one of useful option is -L to change language.

One good source to inspiration, how documentation looks like, is git/Documentation, in terms of format, style and grammar.

References