updating README

README.md

@@ -12,15 +12,32 @@ make build-cli-arm
 
 ## Usage
 ```
-Usage of kasa-exporter:
-  -address string
-        address to listen on
-  -password string
-        password for kasa login
-  -port int
-        port to listen on (default 9500)
-  -username string
-        username for kasa login
+NAME
+  kasa-exporter (rev 756f42e)
+
+FLAGS
+  -l, --log STRING               log level: debug, info, warn, error (default: info)
+  -a, --address STRING           address to listen on
+  -p, --port INT                 port to listen on (default: 9500)
+      --username STRING          username for kasa login
+      --password STRING          password for kasa login
+      --hashed_password STRING   hashed (sha1) password for kasa login
+      --max_registries INT       maximum number of registries to cache (default: 16)
+```
+
+The configuration can also be passed to the program using environment variables prefixed with `KASA_EXPORTER_`.
+
+An example docker compose file would look like:
+
+```yaml
+services:
+  kasa:
+    image: okhalid/kasa-exporter:latest
+    environment:
+      - KASA_EXPORTER_USERNAME=your_tplink_email
+      - KASA_EXPORTER_HASHED_PASSWORD=your_sha1_hashed_password
+    ports:
+      - 9500:9500
 ```
 
 ## Prometheus Config