Polish connector canvas public listing

Rewrite the extension documentation around the GitHub Copilot app experience, add official Connector Namespace guidance, and align marketplace metadata with the public-facing product description.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

extensions/connector-namespaces/extension.mjs

@@ -44,7 +44,7 @@ const session = await joinSession({
         createCanvas({
             id: "connector-namespaces",
             displayName: "MCP Connectors",
-            description: "Browse, connect, and open MCP connectors in the Azure Connector Namespace Sandbox.",
+            description: "Discover, connect, and manage hosted MCP servers from Azure Connector Namespace.",
             inputSchema: {
                 type: "object",
                 properties: {