alloy(role): add documentation

- add README
- add argument_specs
- removed tags

roles/alloy/meta/argument_specs.yaml

@@ -0,0 +1,33 @@
+argument_specs:
+  main:
+    options:
+      alloy_config_default:
+        type: str
+        required: true
+      alloy_config_additional:
+        type: str
+        required: false
+      alloy_blackbox_exporter_config_default:
+        type: str
+        required: false
+      alloy_blackbox_exporter_config_additional:
+        type: str
+        required: false
+      alloy_cap_net_bind_service:
+        type: bool
+        required: false
+        default: false
+      alloy_unpoller_enabled:
+        type: bool
+        required: false
+        default: false
+      alloy_unpoller_unifi_user:
+        type: str
+        required: false
+        default: unpoller
+      alloy_unpoller_unifi_password:
+        type: str
+        required: false
+      alloy_unpoller_unifi_url:
+        type: str
+        required: false