add readme getting started instructions

README.md

@@ -1,3 +1,26 @@
 # GitHub Issue Due Dates Action
 
-
+## How it works:
+1. Add the following to the top of issues you'd like assign due dates to:
+```
+---
+due: 2019-09-19
+---
+```
+2. Create a .github/workflows/workflow.yml file with the following contents:
+```
+name: Main Workflow
+on:
+  schedule:
+    - cron:  '0 * * * *'
+jobs:
+  Ubuntu:
+    name: Add labels to issues
+    runs-on: ubuntu-latest
+    steps:
+      - name: GitHub Issue Due Dates Action
+        uses: alexleventer/github-issue-due-dates-action@master
+        env:
+          GH_TOKEN: "${{ secrets.GH_TOKEN }}"
+```
+3. Generate a GitHub token and add it to your repository secrets.