API summary does not distinguish `init` accessor from `set`

Before , CliAction had a `public bool Exclusive { get; protected set; }` property, and the API summary showed that as a read-only `Exclusive` property with a separate protected `set_Exclusive` method:

After , CliAction has a `public bool Terminating { get; protected init; }` property, and the API summary shows that as a read-only `Terminating` property with a separate protected `set_Terminating` method:

That is, the API summary shows the protected accessor in the same way regardless of whether it is `set` or `init`.

Because replacing a `set` accessor with `init` is a breaking change, their API summaries should differ so that the API compatibility test can fail if such a change is made unexpectedly.