No document/changelog of Scriptable Build Pipeline 1.4.1-preview

https://docs.unity3d.com/Packages/com.unity.scriptablebuildpipeline@1.4/changelog/CHANGELOG.html works just fine for me:

[1.4.1-preview] - 2019-04-16

• Fixed "Path is empty" exception in build cache
• Fixed an edge case where a valid cache entry could be returned for an invalid request
• Added BuildCache.PruneCache API to trim the cache down to a limit, called in the background after a build
• Moved BuildCache menu options and preferences to the "Edit/Prefferences..." window