update readme

Author: james-bruten-mo

track-review-project/README.md

@@ -7,6 +7,11 @@ requested and performed. If a CR hasn't been requested, it will do so when
 moving to the CR state. It will also add the PR author as an assignee if none
 exist.
 
+In order for this to work with forks when reviews are completed, a triggering
+workflow is also required. This can be shown by the "Trigger Project Workflow"
+yaml file below. The "Track Action Project" workflow is triggered by this
+workflow via github "workflow_run" syntax.
+
 It requires a PAT with permissions to write to projects to be added as a secret
 to the repository with the name `PROJECT_ACTION_PAT`. Project edits made using
 this token will be shown as performed by the owner of the token.
@@ -17,10 +22,10 @@ this token will be shown as performed by the owner of the token.
 name: Track Review Project
 
 on:
-  pull_request_target:
-    types: ["opened", "synchronize", "reopened", "edited", "review_requested", "review_request_removed"]
-  pull_request_review:
-  pull_request_review_comment:
+  workflow_run:
+    workflows: [Trigger Review Project]
+    types:
+      - completed
   workflow_dispatch:
 
 jobs:
@@ -34,3 +39,18 @@ jobs:
       project_number: 376
 
 ```
+
+```yaml
+name: Trigger Review Project
+
+on:
+  pull_request_target:
+    types: ["opened", "synchronize", "reopened", "edited", "review_requested", "review_request_removed"]
+  pull_request_review:
+  pull_request_review_comment:
+
+jobs:
+  trigger_project_workflow:
+    uses: MetOffice/growss/.github/workflows/trigger-project-workflow.yaml@develop
+    secrets: inherit
+```