Address changelogs linter offenses at 8-0-stable

This commit addresses the following offenses.

```
$ tools/railspect changelogs .
..........E..

Offenses:

activesupport/CHANGELOG.md:5 CHANGELOG header must start with '*' and 3 spaces
*  Restore the ability to decorate methods generated by `class_attribute`.
^^^^
activesupport/CHANGELOG.md:7 CHANGELOG line must be indented 4 spaces
  It always has been complicated to use Module#prepend or an alias method chain
^^^^
activesupport/CHANGELOG.md:8 CHANGELOG line must be indented 4 spaces
  to decorate methods defined by `class_attribute`, but became even harder in 8.0.
^^^^
activesupport/CHANGELOG.md:10 CHANGELOG line must be indented 4 spaces
  This capability is now supported for both reader and writer methods.
^^^^
activesupport/CHANGELOG.md:12 CHANGELOG line must be indented 4 spaces
  *Jean Boussier*
^^^^
13 changelogs inspected, 5 offenses detected
```

Follow up rails@5c31aba

activesupport/CHANGELOG.md

@@ -2,14 +2,14 @@
 
     *Martin Emde*
 
-*  Restore the ability to decorate methods generated by `class_attribute`.
+*   Restore the ability to decorate methods generated by `class_attribute`.
 
-  It always has been complicated to use Module#prepend or an alias method chain
-  to decorate methods defined by `class_attribute`, but became even harder in 8.0.
+    It always has been complicated to use Module#prepend or an alias method chain
+    to decorate methods defined by `class_attribute`, but became even harder in 8.0.
 
-  This capability is now supported for both reader and writer methods.
+    This capability is now supported for both reader and writer methods.
 
-  *Jean Boussier*
+    *Jean Boussier*
 
 ## Rails 8.0.0 (November 07, 2024) ##