core.js: Adding an example which shows service methods to jsdocs. this is needed to help ensure devs realize they need to include ctx and serverCall as first two params and also to show an async method with both Promise and Callback way of doing it.
core.js: Adding an example which shows service methods to jsdocs.
this is needed to help ensure devs realize they need to include
ctx and serverCall as first two params and also to show an async
method with both Promise and Callback way of doing it.

Change-Id: Id5bfe11bd05bb72bb4e2a70d4671bcd60c752d66

vanadium/js,vanadium/js,vanadium/js,vanadium/js