update RT-Thread v5.2.2

Author: CYFS3

RT-Thread_Source_Code/index.json

@@ -4,6 +4,13 @@
     "description": "RT-Thread source code releases",
     "license": "",
     "releases": [
+        {
+            "version": "5.2.2",
+            "date": "2025-10-31",
+            "description": "https://github.com/RT-Thread/rt-thread/releases/tag/v5.2.2",
+            "size": "181 MB",
+            "url": "https://github.com/RT-Thread-Studio/sdk-rt-thread-source-code/archive/v5.2.2.zip"
+        },
         {
             "version": "5.2.1",
             "date": "2025-05-30",