add branding and mod readme

README.md

@@ -1,10 +1,28 @@
 # Attach to Trello Card action
 
-This action looks for a Trello card URL in the start of a Pull Request description.  If found, will push an attachment to Trello (for use by Trello Github Power-Up).  Optionally, this can be configured to also attach a (redundant) PR comment with link/name, similar to what the Trello Power-up will do, for actions that expect that to be present.
+The purpose of this action is to enable attaching a pull request to a Trello card, from within the PR body.  This is best used with the Trello [Github Power-Up](https://trello.com/power-ups/55a5d916446f517774210004) added to your Trello Boards.  With that enabled, this effectively enables the "Attach Pull Request" action of the Power-Up, but from the Github side (and via a quick URL copy-paste instead of clicking through menus).
+
+The action looks for a Trello card URL at the start of a Pull Request description.  If found, it will add the PR URL as an attachment to Trello.
+
+Optionally, this can be configured to also attach a (redundant) PR comment with link/name, similar to what the Trello Power-up will do, for use cases requiring that.
+
+
+## Events
+
+Workflows using this action should include some/all of the following supported event types: 
+- `pull_request.opened`
+- `pull_request.reopened`
+- `pull_request.edited`
+
+Unsupported actions are ignored.
+
 
 ## Inputs/Outputs
 
-This requires Trello key+token to be supplied from workflow where used (The token, at least, should come from repo Secrets).
+This requires Trello key and token to be supplied from the workflow where used.  The token, at least, should come from repo Secrets.  
+
+There are no outputs.
+
 
 ## Example workflow config:
 ```yml
@@ -21,6 +39,7 @@ jobs:
         with:
           trello-key: ${{ secrets.TRELLO_KEY }}
           trello-token: ${{ secrets.TRELLO_TOKEN }}
+
           ## optional
           # add-pr-comment: true
           ## required if add-pr-comment is true.  secrets.GITHUB_TOKEN is supplied by GH action implicitly.

action.yml

@@ -18,3 +18,6 @@ inputs:
 runs:
   using: 'node12'
   main: 'index.js'
+branding:
+  icon: 'paperclip'  
+  color: 'blue'