Fix "moved artifacts" link (#6083)

Author: BoD

docs/source/migration/4.0.mdx

@@ -12,7 +12,7 @@ While most of the core APIs stayed the same, Apollo Kotlin 4 contains a few bina
 Apollo Kotlin 4 removes some deprecated symbols. We strongly recommend updating to the latest 3.x release and removing deprecated usages before migrating to version 4.
 
 Important changes are:
-* [new package name](#group-id--plugin-id--package-name) and [moved artifacts](#moved-artifacts-)
+* [new package name](#group-id--plugin-id--package-name) and [moved artifacts](#moved-artifacts)
 * [fetch errors do not throw anymore](#fetch-errors-do-not-throw)
 * [the apolloMetadata Gradle configuration is not used anymore](#multi-module-dependson)