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

docs_src/troubleshooting/tutorial002.py

@@ -0,0 +1,15 @@
+from mcp.server import MCPServer
+
+mcp = MCPServer("Weather")
+
+
+@mcp.tool(name="forecast")
+def forecast_today(city: str) -> str:
+    """Today's forecast for one city."""
+    return f"{city}: Rain."
+
+
+@mcp.tool(name="forecast")  # Same name. This registration is dropped.
+def forecast_hourly(city: str, hours: int) -> str:
+    """The next few hours for one city."""
+    return f"{city}: Rain for {hours}h."