Clarify commenting and review submission instructions

Updated wording for commenting options and review submission.

Author: ashis-baral

content/pull-requests/how-tos/review-pull-requests/commenting-on-a-pull-request.md

@@ -48,11 +48,11 @@ To reply to an existing line or file comment, navigate to the comment on either
 {% data reusables.repositories.start-file-comment %}
 1. When you're done:
 
-   * If you only want to add this **one comment**, click **Add single comment**.
+   * If you only want to add this **one comment**, click **Comment**.
 
    * If you want to add **multiple comments**, click **Start a review**, then continue adding comments.
 
-     When you're finished, click **Finish your review**, leave a summary of your review, and click **Submit review**.
+     When you're finished, click **Submit review**, leave a summary of your review, and click **Submit review**.
 
 Anyone watching the pull request or repository will receive a notification of your comments. Batching your comments avoids sending multiple notifications.