updates

README.md

@@ -41,6 +41,8 @@ The StackQL middleware server enables clients to query api backends using a natu
 
 Results can be operated on using SQL functions and operators (including grouping, windowing, and aggregation functions) and then returned to the client as a JSON response.  The following architecture diagram illustrates the StackQL middleware server's components.
 
+### Context Diagram
+
 ```mermaid
 flowchart TB;
    user["User or UserAgent"] -->|submits queries| api["stackql API (Deno Oak)"];