Add instruction how to run devenv

devenv/README.md

@@ -1 +1,19 @@
 # Development environment for the plugin
+
+This docker environments contain preconfigured Zabbix instance with several monitored hosts and preconfigured Grafana with added data source and dashboards for testing. Environment uses plugin built
+from sources, so in order to start environment, run commands from plugin root directory:
+
+```shell
+# Build plugin
+make dist
+
+# Test plugin with Zabbix 6.0
+cd devenv/zabbix60
+docker-compose up -d
+```
+
+If you want to edit sources, do it, rebuild plugin and then restart grafana container:
+
+```shell
+docker-compose restart grafana
+```