Add README

Author: lorenanicole

README.md

@@ -1,2 +1,16 @@
-# go-snapshot-action
-Go Snapshot Action
+# Go Snapshot Action
+
+An action that creates a dependency submission using `go mod graph`.
+
+To configure, you'll need to provide a GitHub token. Additional optional inputs include: `detector-name`, `detector-url`, `detector-version`, and `metadata` - a JSON of max eight keys to provide with the snapshot. 
+
+```
+name: Run snapshot action
+uses: ./go-snapshot-action
+with:
+    token: ${{ secrets.GITHUB_TOKEN }}
+    detector-name: go snapshot action
+    detector-url: ${{ github.server_url }}/${{ github.repository }}
+    detector-version: 1.0.0
+    metadata: '{"lastModified": "22-04-2022"}'
+```