Rebuild the docs around tested examples; shrink README.v2.md to a pitch (#2978)

docs_src/resources/tutorial003.py

@@ -0,0 +1,23 @@
+import base64
+
+from mcp.server import MCPServer
+
+mcp = MCPServer("Bookshop")
+
+
+@mcp.resource("docs://readme", mime_type="text/markdown")
+def readme() -> str:
+    """How to use this server."""
+    return "# Bookshop\n\nSearch the catalog with the `search_books` tool."
+
+
+@mcp.resource("stats://catalog", mime_type="application/json")
+def catalog_stats() -> dict[str, int]:
+    """Live counts for the catalog."""
+    return {"books": 1204, "authors": 391}
+
+
+@mcp.resource("covers://placeholder", mime_type="image/gif")
+def placeholder_cover() -> bytes:
+    """A 1x1 transparent GIF, shown when a book has no cover."""
+    return base64.b64decode("R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7")