[skip ci] Fix typos in UPGRADING

Closes GH-5183

Author: TysonAndre

UPGRADING

@@ -370,7 +370,7 @@ PHP 8.0 UPGRADE NOTES
   . It is now possible to fetch the class name of an object using
     `$object::class`. The result is the same as `get_class($object)`.
     RFC: https://wiki.php.net/rfc/class_name_literal_on_object
-  . New and instanceof can now be used with arbitary expressions, using
+  . New and instanceof can now be used with arbitrary expressions, using
     `new (expression)(...$args)` and `$obj instanceof (expression)`.
     RFC: https://wiki.php.net/rfc/variable_syntax_tweaks
   . Some consistency fixes to variable syntax have been applied, for example

UPGRADING.INTERNALS

@@ -12,7 +12,7 @@ PHP 8.0 INTERNALS UPGRADE NOTES
   i. get_closure() object handler
   j. compare_objects() and compare() object handlers
   k. The 'I' length modifier
-  l. Some VM instructions switched to IS_TMP_VAR result insted of IS_VAR
+  l. Some VM instructions switched to IS_TMP_VAR result instead of IS_VAR
 
 2. Build system changes
   a. Abstract
@@ -91,7 +91,7 @@ PHP 8.0 INTERNALS UPGRADE NOTES
      The 'v' format from the custom snprintf and spprintf implementations has
      been removed. Use the standard 's' format instead.
 
-  l. Some VM instructions switched to IS_TMP_VAR result insted of IS_VAR.
+  l. Some VM instructions switched to IS_TMP_VAR result instead of IS_VAR.
      Actually, all assignments (ZEND_ASSIGN, ZEND_ASSIGN_DIM, ZEND_ASSIGN_OBJ,
      ZEND_ASSIGN_STATIC_PROP), all compound assignments (ZEND_ASSIGN_OP,
      ZEND_ASSIGN_DIM_OP, ZEND_ASSIGN_OBJ_OP, ZEND_ASSIGN_STATIC_PROP_OP) and all