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

docs_src/progress/tutorial001.py

@@ -0,0 +1,12 @@
+from mcp.server import MCPServer
+from mcp.server.mcpserver import Context
+
+mcp = MCPServer("Bookshop")
+
+
+@mcp.tool()
+async def import_catalog(urls: list[str], ctx: Context) -> str:
+    """Import book records from a list of catalog URLs."""
+    for done, url in enumerate(urls, start=1):
+        await ctx.report_progress(done, total=len(urls), message=f"Imported {url}")
+    return f"Imported {len(urls)} records."