Update README

Signed-off-by: Adolfo García Veytia (Puerco) <[email protected]>

README.md

@@ -1,2 +1,56 @@
-# generate-vex
-OpenVEX GitHub action that generates VEX data
+# OpenVEX Generation GitHub Action
+
+This repository contains a GitHub action that enables the automatic generation
+of VEX (Vulnerability Eploitability Exchange) data using the OpenVEX tooling.
+
+## Usage
+
+To start generating openvex data you need to create your VEX feed and generate
+OpenVEX data when you cut a release.
+
+### Initialize your OpenVEX Feed
+
+To generate VEX data, generate golden VEX data in for your project. The easiest
+way to do it is to download [`vexctl`](https://github.com/openvex/vexctl/releases/latest),
+initialize the OpenVEX directory and commit the result:
+
+```bash
+cd myproject
+vexctl generate --init
+git add .openvex
+git commit -sm "initialize OpenVEX Feed"
+```
+
+After pushing the commit, your VEX feed is ready to go! :rocket:
+
+### Generating OpenVEX data at Release Time
+
+To generate OpenVEX data when cutting a release, add a new workflow to your
+repository to create the document from the templates you just created. Here is
+an example:
+
+```yaml
+on:
+  workflow_dispatch:
+  push:
+    tags:
+      - 'v*.*.*'
+jobs:
+  vexctl:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+      - name: Set env
+        run: echo "RELEASE_VERSION=${GITHUB_REF#refs/*/}" >> $GITHUB_ENV
+      - uses: openvex/generate-vex@31b415924ea0d72ed5f2640f1dee59dea6c2770b
+        name: Run vexctl
+        with:
+            product: pkg:generic/hello@${{ env.RELEASE_VERSION }}
+
+
+```
+
+This example workflow generates an openvex document and outputs it to
+the actions log. You can publish the document with your artifacts or attach
+it to container images.