Add missing Langflow link

This fixes a dead link in the client table.

Author: jonathanhefner

docs/clients.mdx

@@ -146,6 +146,7 @@ This page provides an overview of applications that support the Model Context Pr
 [Jenova]: https://www.jenova.ai
 [JetBrains AI Assistant]: https://plugins.jetbrains.com/plugin/22282-jetbrains-ai-assistant
 [Kilo Code]: https://github.com/Kilo-Org/kilocode
+[Langflow]: https://github.com/langflow-ai/langflow
 [LibreChat]: https://github.com/danny-avila/LibreChat
 [LM Studio]: https://lmstudio.ai
 [Lutra]: https://lutra.ai