chore: Update documentation

README.md

@@ -1,3 +1,42 @@
 # GitHub App installation access token generator
 
-[See the documentation in Backstage](https://backstage.idealo.tools/catalog/default/component/github-app-token-generator/docs)
+GitHub Action that can be used to generate an installation access token for a GitHub App. This token can for instance be used to clone repos, given the GitHub App has sufficient permissions to do so.
+
+## Usage
+
+```yaml
+name: Checkout repos
+on: push
+jobs:
+  checkout:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+
+    - uses: idealo/[email protected]
+      id: get-token
+      with:
+        private-key: ${{ secrets.IDEALO_BOT_GH_APP_PRIVATE_KEY }}
+        app-id: ${{ secrets.IDEALO_BOT_GH_APP_ID }}
+
+    - name: Check out an other repo
+      uses: actions/checkout@v2
+      with:
+        repository: owner/repo
+        token: ${{ steps.get-token.outputs.token }}
+```
+
+## Requirements
+
+The action needs two input parameters, `private-key` and `app-id`. To get these, simply create a GitHub App. The private key can be generated and downloaded, and should be added to the repos as a secret.
+
+The installation ID that is used during the creation of the access token is created against the repo running the action. If you need to create the installation ID for a different repo you can use the `repo` input:
+
+```yaml
+uses: idealo/[email protected]
+id: get-token
+with:
+  private-key: ${{ secrets.IDEALO_BOT_GH_APP_PRIVATE_KEY }}
+  app-id: ${{ secrets.IDEALO_BOT_GH_APP_ID }}
+  repo: some/repo
+```

catalog-info.yaml

@@ -9,7 +9,6 @@ metadata:
   annotations:
     github.com/project-slug: idealo/github-app-token-generator
     github.com/team-slug: idealo/compute
-    backstage.io/techdocs-ref: dir:.
   tags:
     - github-action
     - github-app