Update CHANGELOG.md for 1.6.0-beta.1.
Post release version bump.
Remove dup changelog entry.
Merge pull request #4638 from ugisozols/dup_changelog

Remove dup changelog entry.
[DOC release] Clarify reduceComputed's docs

I felt it was unclear what "completely recomputed" meant in the context of non-array or `.[]` (square bracket) dependencies. Hopefully this should help others understand more quickly.
Merge pull request #4642 from Kerrick/patch-1

[DOC release] Clarify reduceComputed's docs