Update usage and README.md

README.md

@@ -1,4 +1,21 @@
-This application bridges Alertmanager alerts to [Gotify](https://gotify.net).
+This application bridges [Prometheus Alertmanager](https://prometheus.io/docs/alerting/latest/alertmanager/) alerts to [Gotify](https://gotify.net/).
+
+# Usage
+```
+usage: alertify.py [-h] [-H]
+
+Bridge between Prometheus Alertmanager and Gotify
+
+optional arguments:
+  -h, --help         show this help message and exit
+  -H, --healthcheck  Simply exit with 0 for healthy or 1 when unhealthy
+
+Three environment variables are required to be set:
+  * GOTIFY_SERVER: hostname of the Gotify server
+  * GOTIFY_PORT: port of the Gotify server
+  * GOTIFY_KEY: app token for alertify
+```
+
 
 # Notes
 * Listens on port 8080 by default.

alertify.py

@@ -127,7 +127,14 @@ if __name__ == '__main__':
         """
         Function to parse the CLI
         """
-        parser = argparse.ArgumentParser()
+        parser = argparse.ArgumentParser(
+            formatter_class=argparse.RawDescriptionHelpFormatter,
+            description='Bridge between Prometheus Alertmanager and Gotify\n',
+            epilog='Three environment variables are required to be set:\n'
+                   '  * GOTIFY_SERVER: hostname of the Gotify server\n'
+                   '  * GOTIFY_PORT: port of the Gotify server\n'
+                   '  * GOTIFY_KEY: app token for alertify'
+        )
 
         parser.add_argument(
             '-H', '--healthcheck',