Update upstream.md

Co-authored-by: Francesco Pham <[email protected]>
Signed-off-by: Stefan Schmidt <[email protected]>

upstream.md

@@ -44,7 +44,7 @@ This fork is no long-term home for most of the changes, though.
 Any change that is also applicable to OpenHarmony upstream we need to propose a
 pull request against the master branch in Gitee. By doing so we get crucial
 feedback from OpenHarmony developers. This will help in the design and
-implementation of changes to fit well into the existing code base. And secondly,
+implementation of changes, to fit well into the existing code base. Additionally,
 any changes viable for upstream inclusion will return to Eclipse Oniro with the next
 release synchronization, reducing the maintenance burden to carry patches downstream.