diff --git a/.res/ghaction-import-gpg.png b/.res/ghaction-import-gpg.png
new file mode 100644
index 0000000..d0bef8b
Binary files /dev/null and b/.res/ghaction-import-gpg.png differ
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0f7b28b..522ad04 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,5 @@
 # Changelog
 
-## 1.0.0 (2019/09/22)
+## 0.1.0 (2020/05/03)
 
 * Initial version
diff --git a/README.md b/README.md
index e3c79b5..adaa56a 100644
--- a/README.md
+++ b/README.md
@@ -10,6 +10,8 @@ GitHub Action to easily import your GPG key to sign commits and tags.
 
 If you are interested, [check out](https://git.io/Je09Y) my other :octocat: GitHub Actions!
 
+![Import GPG key](.res/ghaction-import-gpg.png)
+
 ## Usage
 
 ```yaml
@@ -28,11 +30,21 @@ jobs:
         uses: actions/checkout@v2
       -
         name: Import GPG key
-        uses: crazy-max/ghaction-import-gpg@master
+        uses: crazy-max/ghaction-import-gpg@v1
         env:
           SIGNING_KEY: ${{ secrets.SIGNING_KEY }}
 ```
 
+## Customizing
+
+### environment variables
+
+Following environment variables can be used as `step.env` keys
+
+| Name           | Description                           |
+|----------------|---------------------------------------|
+| `SIGNING_KEY`  | GPG private key exported as an ASCII armored version |
+
 ## How can I help?
 
 All kinds of contributions are welcome :raised_hands:! The most basic way to show your support is to star :star2: the project, or to raise issues :speech_balloon: You can also support this project by [**becoming a sponsor on GitHub**](https://github.com/sponsors/crazy-max) :clap: or by making a [Paypal donation](https://www.paypal.me/crazyws) to ensure this journey continues indefinitely! :rocket: