message: fix: Update MIGRATION for SeverityLevel
diff: @@ -478,11 +478,9 @@ const status = SpanStatus.fromHttpCode(403);
  We deprecated the `Severity` enum in `@sentry/types` and it will be removed in the next major release. We recommend using string literals (typed as `SeverityLevel`) to save on bundle size.
  -`SeverityLevel` and `SeverityLevels` will continue to exist in v7, but they will live in `@sentry/utils` rather than `@sentry/types`. Currently, they live in both, for ease of migration. (`SeverityLevels` isn't included in the examples below because it is only useful internally.)
  -
  ```js
  // New in 6.17.5:
  -import { SeverityLevel } from '@sentry/utils';
  +import { SeverityLevel } from '@sentry/types';
  const levelA = "error" as SeverityLevel;
  