What makes a README file awesome?

Meow Monday ☀️ I recently enjoyed reading this Discussion on insights and best practices to get more stars on GitHub. @zoltanszogyenyi suggested nailing the README file -- the most important of a repo? -- as it's the first thing everyone looks at. So, what makes a README file awesome from your point of view? What are the key elements you'd expect when reading one? Any good example? P.S. By 'awesome,' I mean a file that WOW you, that's resourceful, and makes you want to contribute.