Add a page describing the degraded mode and explaining how to enable it

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Describe the solution you'd like

Enabling the degraded mode has multiple effects that should be listed in the documentation:

// Explicitly disable all the features that are implicitly excluded when the degraded mode is active.
if (options.EnableDegradedMode)
{
    options.DisableAuthorizationStorage = options.DisableTokenStorage = options.DisableRollingRefreshTokens = true;
    options.IgnoreEndpointPermissions = options.IgnoreGrantTypePermissions = true;
    options.IgnoreResponseTypePermissions = options.IgnoreScopePermissions = true;
    options.UseReferenceAccessTokens = options.UseReferenceRefreshTokens = false;
}

https://github.com/openiddict/openiddict-core/blob/186d3d8ddb84d600876e620fe9c236748a7e885b/src/OpenIddict.Server/OpenIddictServerConfiguration.cs#L31-L38

Additional context

No response

Start with src/OpenIddict.Server/OpenIddictServerConfiguration.cs around lines 31-38 and review the EnableDegradedMode option and its related settings. Add a documentation page explaining how to enable degraded mode and list each effect shown in the issue; done means the behavior and configuration steps are clearly documented.