`ref readonly` parameters only say `ref` in signatures

### Describe the issue or suggestion

For example the `ReadOnlySpan` constructor takes a `ref readonly T`, however the documentation lists the parameter as `ref T reference` instead, leaving out important information about the signature: https://learn.microsoft.com/en-us/dotnet/api/system.readonlyspan-1.-ctor?view=net-9.0#system-readonlyspan-1-ctor(-0@)