Fix README instructions on how to start the server and add how to check if it is running

[tiagostutz]

Currently the README instructions does not lead to a running server and doesn't give directions on how to check whether the server is correctly running.

There could be an instruction such as

To check the server running, just open your browser and type http://localhost:7070/v1/choice

Or could have a curl to be copy-paste.

[trolzen]

Hi! Is it OK if I start working on this issue?

[prkbuilds]

Hi @tiagostutz Can I work on this issue, as a good first issue?

[tiagostutz]

Hi @tiagostutz Can I work on this issue, as a good first issue?

Unfortunately I'm not the maintainer of this project anymore =/

But I have this other project with good first issue that you may find something nice to work on:

https://github.com/tiagostutz/java-code-assignment/issues