NuGet introduced embedded markdown Readme support in May 2021. Now the updated gallery design displays this readme file on the package page if it's included. Looks like most runtime packages don't have readme embedded (neither markdown nor plaintext), and for them it fallbacks to description from nuspec. This leads to experience like this:

A lot of space is unused here. It could be filled with some more introductory information or simple usage example. And also listed "Commonly used types" could be links to their API docs. That's how package with markdown readme looks like:

Could we add markdown readme files for runtime packages?

Progress:

• microsoft.extensions.configuration
• microsoft.extensions.configuration.json
• system.configuration.configurationmanager
• system.text.json
• microsoft.extensions.configuration.binder
• microsoft.extensions.configuration.abstractions
• System.Runtime.Caching

For up-to-date checklist, see PR #91210

See also:

• Write a high-quality README for NuGet packages
• Package Readme guidelines
• Example PR with new Readme template