To remember for next time I open-source a package: the README should have an example on how the package works front and centre. It doesn’t have to be a large, and probably shouldn’t be complicated, but it should show your package doing something useful.
Installation instructions are helpful, but unless they differ from every other package for a language or framework, they’re not super necessary. Your users can probably guess as to how to install your package if they’ve done it before.
But they’ll have no idea how to use your package. What do you need to do to initialise it? What are the major types and methods? What’s the minimum you need to do to get something working?
An example demonstrating these should give enough information about how the package work and how it’s structured. At the very least it will show what the more important types and attributes are, so the user can use that as a launching place while browsing the documentation. But sometimes, if it’s a client for something that the user knows what to expect, a user could probably gauge enough about how it works from the example itself.
So, examples. Have them. Front and centre.