Some projects such as user applications should include examples of usage varying of the complexity from a simple "Hello world"-esque example to a real-life example that the developer uses.
This gives a quick introduction to the tool as well as subtly giving hints about what you can do with the program.
Examples include the manual pages from [[https://www.freebsd.org/][the FreeBSD project]] where each tool is given a dedicated section for example usage.
Another that stuck out to me is the README of [[https://github.com/naelstrof/maim/tree/b1b28fcb0c3a44e699fd879189316440b7edff22][maim]], a screenshot capture tool, where one of the examples demonstrate that you can pipe binary output which leads to useful things such as [[https://github.com/naelstrof/maim/tree/b1b28fcb0c3a44e699fd879189316440b7edff22][OCR selection]] or a colorpicker.
This makes it easier to skim (see [[id:5c1e9540-9663-4512-8c84-05529ad22212][Speedreading is all about skimming well]]) and to [[id:9a11ef31-b2a7-43a9-a7a9-48f191838c6e][Prefer referencing over remembering]].