Add information on how to run when the previous step failed

README.md

@@ -23,6 +23,17 @@ steps:
     path: path/to/artifact
 ```
 
+To upload artifacts only when the previous step of a job failed, use [`if: failure()`](https://help.github.com/en/articles/contexts-and-expression-syntax-for-github-actions#job-status-check-functions):
+
+```yaml
+- uses: actions/upload-artifact@master
+  if: failure()
+  with:
+    name: my-artifact
+    path: path/to/artifact
+```
+
+
 ## Where does the upload go?
 In the top right corner of a workflow run, once the run is over, if you used this action, there will be a `Artifacts` dropdown which you can download items from. Here's a screenshot of what it looks like<br/>
 ![Artifacts Screenshot](https://user-images.githubusercontent.com/3685876/62906968-1b4aff80-bd3f-11e9-8815-9058eb05692a.png)