Mention reviewing the source diff (#17141)

Author: hubwriter

content/github/collaborating-with-issues-and-pull-requests/reviewing-dependency-changes-in-a-pull-request.md

@@ -36,7 +36,7 @@ Dependency review supports the same languages and package management ecosystems
 
    ![The file filter menu](/assets/images/help/pull_requests/file-filter-menu-json.png)
 
-1. On the right of the header for a manifest or lock file, display the dependency review by clicking the rich diff button.
+1. On the right of the header for a manifest or lock file, display the dependency review by clicking the **{% octicon "file" aria-label="The rich diff icon" %}** rich diff button.
 
    ![The rich diff button](/assets/images/help/pull_requests/dependency-review-rich-diff.png)
 
@@ -69,6 +69,4 @@ Dependency review supports the same languages and package management ecosystems
    * The severity of the vulnerability.
    * The version of the dependency in which the vulnerability was fixed. If you are reviewing a pull request for someone, you might ask the contributor to update the dependency to the patched version, or a later release.
 
-1. You can return to the original view of the file by clicking the source diff button. 
-
-   ![The source diff button](/assets/images/help/pull_requests/dependency-review-source-diff.png)
+{% data reusables.repositories.return-to-source-diff %}

content/github/collaborating-with-issues-and-pull-requests/reviewing-proposed-changes-in-a-pull-request.md

@@ -37,9 +37,11 @@ If the pull request contains changes to dependencies you can use the dependency
 
 {% data reusables.repositories.changed-files %}
 
-1. On the right of the header for a manifest or lock file, display the dependency review by clicking the rich diff button.
+1. On the right of the header for a manifest or lock file, display the dependency review by clicking the **{% octicon "file" aria-label="The rich diff icon" %}** rich diff button.
 
    ![The rich diff button](/assets/images/help/pull_requests/dependency-review-rich-diff.png)
+
+{% data reusables.repositories.return-to-source-diff %}
 {% endif %}
 
 ### Marking a file as viewed

data/reusables/repositories/return-to-source-diff.md

@@ -0,0 +1,5 @@
+1. You may also want to review the source diff, because there could be changes to the manifest or lock file that don't change dependencies, or there could be dependencies that {% data variables.product.prodname_dotcom %} can't parse and which, as a result, don't appear in the dependency review.
+
+   To return to the source diff view, click the **{% octicon "code" aria-label="The source diff icon" %}** button.
+
+   ![The source diff button](/assets/images/help/pull_requests/dependency-review-source-diff.png)