Add Build a Remote MCP client guide (#21518)

Author: dinasaur404

src/content/docs/agents/guides/build-mcp-client.mdx

@@ -0,0 +1,9 @@
+---
+pcx_content_type: navigation
+title: Build a Remote MCP Client
+external_link: https://github.com/cloudflare/ai/tree/main/demos/mcp-client
+sidebar:
+  order: 7
+head: []
+description: Build an AI Agent that acts as a remote MCP client. 
+---