Update getting-started.adoc adding notes to a request

[Ivan-Igorevich]

In an example of Jmix docs there are requests, that return user information. A cURL sample is given as follows

curl -X GET http://localhost:8080/rest/entities/User -H "Authorization: Bearer <access_token>"   

where -X key should be omitted in request, and project prefix added to an entity name

curl http://localhost:8080/rest/entities/smp_User -H "Authorization: Bearer <access_token>"