* [Feature] Add endpoint command, refactor Makefile to cross build target

* Add missing documentation and polish

* Fix bug

* Polish

* Re-organize documentations and collapse details for simplicity

* Add some common use cases

* Polish

* Add ascii graph

Set up the graphql client, schema and implement a service command
for reference

Modifications:

- Set up GraphQL client
- Implement service ls command

Result:

GraphQL client can be reused by other commands