Describe the application design

Explain how the work is split among the contract and the service.

README.md

@@ -2,3 +2,10 @@
 
 This is an example [Linera](https://linera.io) application that shows how to use the
 [Atoma Network](https://atoma.network) to execute AI inference and verify it on-chain.
+
+## Application Design
+
+Any microchain can use the service to perform a query to the Atoma Network. The result is then
+included in the operation that's added to the block, together with a certificate that the result
+was produced by the Atoma Network. When the block is created, the contract is responsible for
+checking the certificate.