Update changelog from #9128 with author name

And improve AS changelog a bit [ci skip]

activesupport/CHANGELOG.md

@@ -5,6 +5,8 @@
     the default behaviour of Date#toJSON() in recent versions of Chrome, Safari and
     Firefox.
 
+    *James Harton*
+
 *   Improve `String#squish` to handle Unicode whitespace. *Antoine Lyset*
 
 *   Standardise on `to_time` returning an instance of `Time` in the local system timezone
@@ -19,8 +21,8 @@
 
     *Yves Senn*
 
-*   Hash.from_xml raises when it encounters type="symbol" or type="yaml".
-    Use Hash.from_trusted_xml to parse this XML.
+*   `Hash.from_xml` raises when it encounters `type="symbol"` or `type="yaml"`.
+    Use `Hash.from_trusted_xml` to parse this XML.
 
     CVE-2013-0156