Update readme

README.md

@@ -1,2 +1,26 @@
 # imposter
-Tool to fake GitHub wehbook events
+Tool to fake GitHub wehbook events.
+
+## Setup
+- Install dependencies with `composer install`.
+- Duplicate the `.env.example` file to `.env`
+- Adjust settings in `.env`
+
+## Usage
+To spoof a pull request merge event, use:
+```
+php spoof styxit/imposter myBrach develop
+```
+
+This will fake an event as if branch "mybranch" was merged into branch "develop", for repository "styxit/imposter".
+
+Use `php spoof --help` to get more info about the command.
+
+## Config
+In the `.env` the following options can be specified:
+
+##### DESTINATION_URL
+This is the url to which the event is POST-ed. Usually your own webhook.
+
+##### GITHUB_SECRET
+The secret string you provided when setting up the webhook at GitHub. This used to sign your request.