Creating releases... (#435)

* Create releases.md

* (SQUASH) make note about keys

Documentation/releases.md

@@ -0,0 +1,25 @@
+## Making a dex Release
+
+1. Make sure you've [uploaded your GPG key](https://github.com/settings/keys).
+
+1. Make a new clone of the dex repo:
+
+  ```console
+  $ git clone git@github.com:coreos/dex.git
+  $ cd dex
+  ```
+
+1. Tag with the release name:
+
+   ```console
+   git tag -s v0.4.0
+   ```
+
+1. Push the change:
+    ```console
+    git push origin v0.4.0
+    ```
+
+1. Make a release with release notes here:
+    https://github.com/coreos/dex/releases
+