docs: clarify streamable_http_path configuration when mounting servers (#1172)

examples/snippets/servers/streamable_http_basic_mounting.py

@@ -0,0 +1,28 @@
+"""
+Basic example showing how to mount StreamableHTTP server in Starlette.
+
+Run from the repository root:
+    uvicorn examples.snippets.servers.streamable_http_basic_mounting:app --reload
+"""
+
+from starlette.applications import Starlette
+from starlette.routing import Mount
+
+from mcp.server.fastmcp import FastMCP
+
+# Create MCP server
+mcp = FastMCP("My App")
+
+
+@mcp.tool()
+def hello() -> str:
+    """A simple hello tool"""
+    return "Hello from MCP!"
+
+
+# Mount the StreamableHTTP server to the existing ASGI server
+app = Starlette(
+    routes=[
+        Mount("/", app=mcp.streamable_http_app()),
+    ]
+)