Update README.md

Author: xmlking

service/account/README.md

@@ -9,7 +9,7 @@ graph LR;
     A(fa:fa-user Account µS)--gRPC-->G(Greeter µS) & E(Emailer µS);
     A & G & E -.-> L[Logger]
     end
-    A ==lockup==> SR[[fa:fa-database Service Registry]];
+    A ==lookup==> SR[[fa:fa-database Service Registry]];
     style SR fill:#f9f,stroke:#333,stroke-width:4px
 ```