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."

docs_src/progress/tutorial002.py

@@ -0,0 +1,21 @@
+from collections.abc import AsyncIterator
+
+from mcp.server import MCPServer
+from mcp.server.mcpserver import Context
+
+mcp = MCPServer("Bookshop")
+
+
+async def fetch_records(feed_url: str) -> AsyncIterator[str]:
+    for title in ("Dune", "Neuromancer", "Hyperion"):
+        yield f"{feed_url}#{title}"
+
+
+@mcp.tool()
+async def import_feed(feed_url: str, ctx: Context) -> str:
+    """Import every record a catalog feed yields."""
+    imported = 0
+    async for record in fetch_records(feed_url):
+        imported += 1
+        await ctx.report_progress(imported, message=f"Imported {record}")
+    return f"Imported {imported} records."