Here are the traditional best practices of how README files should look:

“The distribution should contain a file named README with a general overview of the package:

the name of the package;

the version number of the package, or refer to where in the package the version can be found;

a general description of what the package does;

a reference to the file INSTALL, which should in turn contain an explanation of the installation procedure;

a brief explanation of any unusual top-level directories or files, or other hints for readers to find their way around the source;

a reference to the file which contains the copying conditions. The GNU GPL, if used, should be in a file called COPYING. If the GNU LGPL is used, it should be in a file called COPYING.LESSER.”

— GNU Coding Standards, https://www.gnu.org/prep/standards/html_node/Releases.html#i... (July 1, 2021)

“Good things to have in the README include:

1. A brief description of the project.

2. A pointer to the project website (if it has one)

3. Notes on the developer's build environment and potential portability problems.

4. A roadmap describing important files and subdirectories.

5. Either build/installation instructions or a pointer to a file containing same (usually INSTALL).

6. Either a maintainers/credits list or a pointer to a file containing same (usually CREDITS).

7. Either recent project news or a pointer to a file containing same (usually NEWS).”

— Software Release Practice HOWTO, https://tldp.org/HOWTO/Software-Release-Practice-HOWTO/distp... (Revision 4.1)