If you’re a plugin developer, you may want to check out the WordPress Plugin Readme File Generator.
This convenient tool lets you go through a checklist of fill-in-the-blank boxes to help you make up your readme files for your plugin.
The generator’s first section presents a list of required fields.
The required fields include the following:
Requires at least (lowest version the plugin will work on)
Tested up to (highest version plugin has been tested on)
Stable Tag (the Subversion “tag” of the latest stable version)
Short Description (150 characters max – the generator conveniently keeps track of how many characters you’ve used)