update dropdown menu (#1402)

Author: leofang

cuda_core/docs/nv-versions.json

@@ -3,6 +3,10 @@
         "version": "latest",
         "url": "https://nvidia.github.io/cuda-python/cuda-core/latest/"
     },
+    {
+        "version": "0.5.0",
+        "url": "https://nvidia.github.io/cuda-python/cuda-core/0.5.0/"
+    },
     {
         "version": "0.4.2",
         "url": "https://nvidia.github.io/cuda-python/cuda-core/0.4.2/"