Update README and fix #34

README.md

@@ -6,7 +6,7 @@ This includes runs with a [status](https://docs.github.com/en/rest/reference/che
 
 ## How does it work?
 
-When you `git push`, this GitHub Action will capture the current Branch and SHA. It will query GitHub's API to find previous workflow runs that match the Branch but do not match the SHA. These in-progress runs will be cancelled leaving only the latest run.
+When you `git push`, this GitHub Action will capture the current Branch and SHA. It will query GitHub's API to find previous workflow runs that match the Branch but do not match the SHA. These in-progress runs will be cancelled leaving only this run.
 
 Read more about the [Workflow Runs API](https://docs.github.com/en/rest/reference/actions#workflow-runs).
 
@@ -54,6 +54,24 @@ jobs:
 
 _Note_: `workflow_id` accepts a comma separated list of IDs.
 
+Because this action can only cancel workflows if it is actually being run, it only helps if the pipeline isn't saturated and there are still runners available to schedule the workflow.
+By default, this action does not cancel any workflows older than itself. The optional flag ``all_but_latest`` switches to a mode where the action also cancels itself and all later-scheduled workflows but the last one.
+
+```yml
+name: Cancel
+on: [push]
+jobs:
+  cancel:
+    name: 'Cancel Previous Runs'
+    runs-on: ubuntu-latest
+    timeout-minutes: 3
+    steps:
+      - uses: styfle/cancel-workflow-action@0.5.0
+        with:
+          all_but_latest: true
+          access_token: ${{ github.token }}
+```
+
 At the time of writing `0.5.0` is the latest release but you can select any [release](https://github.com/styfle/cancel-workflow-action/releases).
 
 ## Contributing