Fix Java migration from 5.x to 6.0 (#4982)

* Fix Java migration from 5.x to 6.0

* Mention upgrade of spring boot

src/platforms/java/migration.mdx

@@ -10,6 +10,7 @@ description: "Learn about migrating from io.sentry:sentry 1.x to io.sentry:sentr
 * Kotlin `languageVersion` is upgraded to `1.4`.
 * `Gson` is removed as a transitive dependency and vendored in the SDK.
   * Protocol classes now implement the `JsonSerializable` and `JsonDeserializer` interfaces.
+* Spring Boot has been upgraded to `2.5.13`
 * `SentryOptions#shutdownTimeout` is renamed to `shutdownTimeoutMillis`.
 * Removed `@Deprecated` and `@ApiStatus.ScheduledForRemoval` methods
   * `ITransaction#setRequest`
@@ -22,7 +23,7 @@ description: "Learn about migrating from io.sentry:sentry 1.x to io.sentry:sentr
   * `SentryOptions#setEnableSessionTracking`
   * `sentry.enable-tracing` property
   * `SentrySpringRequestListener`, `SentrySpringFilter` is used instead.
-  * `SentryUserProviderEventProcessor` and `SentryUserProvider`, `SentryUserFilter` is used instead.
+  * `SentryUserProviderEventProcessor`, please use `SentryUserProvider` instead.
 * `SentryOptions#enableScopeSync` is now enabled by default.
 * `ISpan` now has higher precision using the `System#nanoTime` instead of milliseconds.
 * `TransactionNameProvider` is now an interface and `SpringMvcTransactionNameProvider` is the default implementation.