UPGRADING and UPGRADING.INTERNALS for SVG and extensible image API

UPGRADING

@@ -40,6 +40,11 @@ PHP 8.5 UPGRADE NOTES
 - DOM:
   . Added Dom\Element::$outerHTML.
 
+- Standard:
+  . getimagesize() now supports SVG images when ext-libxml is also loaded.
+    Similarly, image_type_to_extension() and image_type_to_extension()
+    now also handle IMAGETYPE_SVG.
+
 - XSL:
   . The $namespace argument of XSLTProcessor::getParameter(),
     XSLTProcessor::setParameter() and XSLTProcessor::removeParameter()
@@ -120,6 +125,9 @@ PHP 8.5 UPGRADE NOTES
 - POSIX:
   . POSIX_SC_OPEN_MAX.
 
+- Standard:
+  . IMAGETYPE_SVG when libxml is loaded.
+
 ========================================
 11. Changes to INI File Handling
 ========================================

UPGRADING.INTERNALS

@@ -22,6 +22,12 @@ PHP 8.5 INTERNALS UPGRADE NOTES
 3. Module changes
 ========================
 
+- Standard:
+  . The functionality of getimagesize(), image_type_to_mime_type(),
+    and image_type_to_extension() is now extensible using the internal APIs
+    php_image_register_handler() and php_image_unregister_handler() in
+    php_image.h.
+
 ========================
 4. OpCode changes
 ========================