Add dashboard to Grafana community built dashboards (#3)

Add dashboard to Grafana Official & community built dashboards. Rework README to describe import from Grafana Official & community built dashboards, separate build section cause it is not a obligatory stage for using dashboard now.

Author: DifferentialOrange

README.md

@@ -1,5 +1,25 @@
 # Tarantool Grafana dashboard
 
+Dashboard for Tarantool application and database server monitoring, based on [grafonnet](https://github.com/grafana/grafonnet-lib) library.
+
+Our pages on Grafana Official & community built dashboards: [InfluxDB](https://grafana.com/grafana/dashboards/12567).
+
+You can find screenshots and short description of contents on Grafana pages.
+
+# How to import
+
+* Open Grafana import menu.
+
+![Grafana import button in v6.6.0](./docs/grafana_import_v6.png)
+
+* Paste dashboard id (`12567` for InfluxDB) or link to dashboard (https://grafana.com/grafana/dashboards/12567 for InfluxDB) or upload json file (download it from Grafana page: [InfluxDB](https://grafana.com/grafana/dashboards/12567); or build it by yourself).
+
+* Set dashboard name, folder, uid (if needed), and metrics database parameters (i.e., InfluxDB source and measurement).
+
+![Grafana import setup in v6.6.0 for InfluxDB](./docs/grafana_import_setup_v6.png)
+
+# How to build
+
 ## Requirements and setup
 
 1. Install [go-jsonnet](https://github.com/google/go-jsonnet) compiler. We use v0.16.0. 
@@ -12,13 +32,11 @@
 
 ```docker-compose up -d``` will start 5 containers: Tarantool, Telegraf, InfluxDB, Prometheus and Grafana, which build cluster with two fully operational metrics datasources (InfluxDB and Prometheus), extracting metrics from Tarantool instance. We recommend using the exact versions we use in experimental cluster (e.g. Grafana v6.6.0). 
 
-## Usage
-
-Currently we provide only InfluxDB-based dashboard template. 
+## How to compile dashboard
 
 ### InfluxDB dashboard
 
-* Compile board template with
+Compile board template with
 ```bash
 jsonnet -J ./vendor/ ./tarantool/dashboard.libsonnet -o ./output.json
 ```
@@ -28,16 +46,6 @@ jsonnet -J ./vendor/ ./tarantool/dashboard.libsonnet | xclip -selection clipboar
 ```
 to put json template into clipboard.
 
-* Open Grafana import menu.
-
-![Grafana import button in v6.6.0](./docs/grafana_import_v6.png)
-
-* Paste json template from clipboard or upload json template file.
-
-* Set dashboard name, folder, uid (if needed), InfluxDB source and measurement of your project's metrics.
-
-![Grafana import setup in v6.6.0](./docs/grafana_import_setup_v6.png)
-
 ## Tests
 
 You can run tests with `./tests.sh` script. `jsonnet` and `jsonnetfmt` must be added to terminal PATH variable.