Add documentation to account for all cli mas options and standardise format

docs/reference/cli/worker.md

@@ -0,0 +1,13 @@
+# `worker`
+
+Global options:
+- `--config <config>`: Path to the configuration file.
+- `--help`: Print help.
+
+## `worker`
+
+Runs the authentication service worker.
+
+```
+$ mas-cli worker
+```