add initial version for release candidates

ha_addons/templates/rc_data.json

@@ -0,0 +1,10 @@
+
+{
+    "name": "TSUN-Proxy (Release Candidate)",
+    "description": "MQTT Proxy for TSUN Photovoltaic Inverters",
+    "version": "rc",
+    "image": "ghcr.io/s-allius/tsun-gen3-addon",
+    "slug": "tsun-proxy-rc",
+    "advanced": true,
+    "stage": "experimental"
+}