docs[patch]: moved semadb.mdx file (#14204)

SemaDB.mdx file was placed with additional sub-folder:
`https://python.langchain.com/docs/integrations/providers/providers/semadb`
- Moved file to the
`https://python.langchain.com/docs/integrations/providers/semadb`
- Added a redirect for the file URL

docs/vercel.json

@@ -492,6 +492,10 @@
       "source": "/docs/integrations/providers/cassandra",
       "destination": "/docs/integrations/providers/astradb"
     },
+    {
+      "source": "/docs/integrations/providers/providers/semadb",
+      "destination": "/docs/integrations/providers/semadb"
+    },
     {
       "source": "/docs/integrations/vectorstores/vectorstores/semadb",
       "destination": "/docs/integrations/vectorstores/semadb"