Update `sentry-docs` with Configuration/Filtering for Sentry Logs integrations

[Flash0ver]

Description

Document the (behavioral breaking) changes from #4700.

See

• https://github.com/getsentry/sentry-dotnet/pull/4700#discussion_r2561156282
• https://github.com/getsentry/sentry-dotnet/pull/4700#discussion_r2561153808

Also add to v6-Migration-Guide.

Document

• Breadcrumbs and Events via
  • SentryLoggingOptions.MinimumBreadcrumbLevel
  • SentryLoggingOptions.MinimumEventLevel
  • SentryLoggingOptionsExtensions.AddLogEntryFilter
• Structured Logs via
  • appsettings.json
  • appsettings.{HostEnvironment}.json
  • logging.AddFilter("Microsoft", LogLevel.Warning);
  • ...

See also

• https://github.com/getsentry/sentry-dotnet/pull/4700#discussion_r2569961190

[linear[bot]]

NET-541