Update README.md

README.md

@@ -6,7 +6,7 @@ GitHub Action that posts a message to a Slack channel
 
 ### `token`
 
-**Required** The Slack auth token
+**Optional** The Slack auth token.  This is only required if environment variable `SLACK_BOT_TOKEN` is not set.
 
 ### `channel`
 
@@ -24,5 +24,5 @@ GitHub Action that posts a message to a Slack channel
   with:
     token: ${{ secrets.SLACK_API_TOKEN }}
     channel: "#general"
-    text: ":tada: This is a test from the ${{env.GITHUB_ACTION}} workflow! <https://github.com/ynab/slack-post-message-action|Action Documentation>"
-```
+    text: ":tada: This is a test from the $GITHUB_ACTION} workflow! <https://github.com/ynab/slack-post-message-action|Action Documentation>"
+```