docs: restructure into topical sections and add the four most-asked-for pages (#3044)

docs_src/deploy/tutorial004.py

@@ -0,0 +1,23 @@
+from mcp.server.mcpserver import Context, MCPServer
+from mcp.server.subscriptions import SubscriptionBus
+
+NOTES = {"todo": "buy milk"}
+
+
+def make_server(bus: SubscriptionBus) -> MCPServer:
+    """Every replica gets its own server object; all of them hold the same bus."""
+    mcp = MCPServer("Notebook", subscriptions=bus)
+
+    @mcp.resource("note://{name}")
+    def note(name: str) -> str:
+        """One note, by name."""
+        return NOTES[name]
+
+    @mcp.tool()
+    async def edit_note(name: str, text: str, ctx: Context) -> str:
+        """Replace a note's text."""
+        NOTES[name] = text
+        await ctx.notify_resource_updated(f"note://{name}")
+        return "saved"
+
+    return mcp