Added docs to http_api
Added docs to http_api

Finished the documentation of API HTTP

Notes: 
· Data source proxy calls not documented - Too long request/response text.
· Dashboard from JSON file no do documented - Need more study to underestand how it works.
grafana/grafana,grafana/grafana,grafana/grafana,grafana/grafana,grafana/grafana,grafana/grafana,grafana/grafana