docs(serviceprovider): wip

On-behalf-of: @SAP christopher.junk@sap.com
Signed-off-by: Christopher Junk <christopher.junk@sap.com>

Author: christophrj

docs/about/design/service-provider-design.md

@@ -64,6 +64,7 @@ sequenceDiagram
     %% messages
     usr->>sp: request domain service through ServiceProviderAPI
     sp->>ds: deploys
+    sp-->>usr: installs DomainServiceAPI in user MCP
     usr->>ds: uses domain service through DomainServiceAPI
 ```