Roles can now have descriptions

Roles can now have human readable descriptions alongside the role name. This may be useful on larger sites to document why a role exists and why you might want to grant it to a user (or alternatively why you might not want to do this).

Correspondingly, \Drupal\user\RoleInterface has gained two new methods:

public function getDescription(): string;
public function setDescription(string $description): static;

These are used to get and set the description respectively on a Role entity.