Prepare for 12.0.0-beta.6 release (#7772)

Author: fhammerschmidt

CHANGELOG.md

@@ -10,14 +10,12 @@
 > - :nail_care: [Polish]
 > - :house: [Internal]
 
-# 12.0.0-beta.6 (Unreleased)
+# 12.0.0-beta.6
 
 #### :boom: Breaking Change
 
 - `rescript format` no longer accepts `--all`. All (non-dev) files of the current rescript.json are now formatted by default. https://github.com/rescript-lang/rescript/pull/7752
 
-#### :eyeglasses: Spec Compliance
-
 #### :rocket: New Feature
 
 - Add new Stdlib helpers: `String.capitalize`, `String.isEmpty`, `Dict.size`, `Dict.isEmpty`, `Array.isEmpty`, `Map.isEmpty`, `Set.isEmpty`. https://github.com/rescript-lang/rescript/pull/7516
@@ -26,8 +24,6 @@
 
 - Fix issue with ast conversion (for ppx use) on functions with attributes on first argument. https://github.com/rescript-lang/rescript/pull/7761
 
-#### :memo: Documentation
-
 #### :nail_care: Polish
 
 - `rescript format` now has a `--dev` flag that works similar to `rescript clean`. https://github.com/rescript-lang/rescript/pull/7752