[DOCS] Integrate the 8.x changelog into the main changelog

Now the changelog up to the latest feature release 8.7.0 is
part of the `main` changelog.

This makes it easier to see what has changed after the last
feature release.

Also, this makes it clear in which release some methods were
deprecated, avoid the impression that methods got both
deprecated and removed in the same release.

Also autoformat the changelog.

Author: oliverklee

CHANGELOG.md

@@ -13,29 +13,17 @@ Please also have a look at our
 - Partial support for CSS Color Module Level 4:
     - `rgb` and `rgba`, and `hsl` and `hsla` are now aliases (#797}
     - Parse color functions that use the "modern" syntax (#800)
-- Add official support for PHP 8.4 (#657)
-- Support arithmetic operators in CSS function arguments (#607)
-- Add support for inserting an item in a CSS list (#545)
 - Add a class diagram to the README (#482)
-- Add support for the `dvh`, `lvh` and `svh` length units (#415)
 - Add more tests (#449)
 
 ### Changed
 
 - Use more native type declarations and strict mode
   (#641, #772, #774, #778, #804)
-- Mark parsing-internal classes and methods as `@internal` (#674)
-- Block installations on unsupported higher PHP versions (#691)
-- Improve performance of `Value::parseValue` with many delimiters by refactoring
-  to remove `array_search()` (#413)
 - Add visibility to all class/interface constants (#469)
 
 ### Deprecated
 
-- Deprecate `Parser::setCharset()` and `Parser::getCharset()` (#688)
-- Deprecate the expansion of shorthand properties (#578, #580, #579, #577, #576,
-  #575, #574, #573, #572, #571, #570, #569, #566, #567, #558)
-
 ### Removed
 
 - Remove `Parser::setCharset/getCharset` (#808)
@@ -50,11 +38,6 @@ Please also have a look at our
 
 - Don't render `rgb` colors with percentage values using hex notation (#803)
 - Parse `@font-face` `src` property as comma-delimited list (#790)
-- Fix type errors in PHP strict mode (#664)
-- Fix undefined local variable in `CalcFunction::parse()` (#593)
-- Fix PHP notice caused by parsing invalid color values having less than 6
-  characters (#485)
-- Fix (regression) failure to parse at-rules with strict parsing (#456)
 
 ### Documentation
 
@@ -63,6 +46,57 @@ Please also have a look at our
 @ziegenberg is a new contributor to this release and did a lot of the heavy
 lifting. Thanks! :heart:
 
+## 8.7.0: Add support for PHP 8.4
+
+### Added
+
+- Add support for PHP 8.4 (#675, #701, #746, #751)
+
+### Changed
+
+- Mark parsing-internal classes and methods as `@internal` (#711)
+- Block installations on unsupported higher PHP versions (#691)
+
+### Deprecated
+
+- Deprecate the expansion of shorthand properties (#719)
+- Deprecate `Parser::setCharset()` and `Parser::getCharset()` (#703)
+
+### Fixed
+
+- Fix type errors in PHP strict mode (#695)
+
+## 8.6.0
+
+### Added
+
+- Support arithmetic operators in CSS function arguments (#607)
+- Add support for inserting an item in a CSS list (#545)
+- Add support for the `dvh`, `lvh` and `svh` length units (#415)
+
+### Changed
+
+- Improve performance of `Value::parseValue` with many delimiters by refactoring
+  to remove `array_search()` (#413)
+
+## 8.5.2
+
+### Changed
+
+- Mark all class constants as `@internal` (#500)
+
+### Fixed
+
+- Fix undefined local variable in `CalcFunction::parse()` (#593)
+
+## 8.5.1
+
+### Fixed
+
+- Fix PHP notice caused by parsing invalid color values having less than
+  6 characters (#485)
+- Fix (regression) failure to parse at-rules with strict parsing (#456)
+
 ## 8.5.0
 
 ### Added