Say "support for" instead of "support of"

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: serhiy-storchaka

Doc/library/decimal.rst

@@ -1188,7 +1188,7 @@ In addition to the three supplied contexts, new contexts can be created with the
       they have in the original context.
 
       .. versionchanged:: next
-         Added support of :func:`copy.replace`.
+         Added support for :func:`copy.replace`.
 
    .. method:: copy_decimal(num, /)