README updated

README.md

@@ -21,6 +21,7 @@ Note: fci - full container ID
 | **docker.discovery** | LLD discovering | Only running containers are discovered.<br>Additional Docker permissions are needed, when you want to see container name (human name) in metrics/graphs instead of short container ID |  
 | **docker.mem[fci,mmetric]** | Memory metrics | mmetric - any available memory metric in the pseudo-file memory.stat, e.g.: *cache, rss, mapped_file, pgpgin, pgpgout, swap, pgfault, pgmajfault, inactive_anon, active_anon, inactive_file, active_file, unevictable, hierarchical_memory_limit, hierarchical_memsw_limit, total_cache, total_rss, total_mapped_file, total_pgpgin, total_pgpgout, total_swap, total_pgfault, total_pgmajfault, total_inactive_anon, total_active_anon, total_inactive_file, total_active_file, total_unevictable* |
 | **docker.cpu[fci,cmetric]** | CPU metrics | cmetric - any available CPU metric in the pseudo-file cpuacct.stat, e.g.: *system, user*<br>Jiffy CPU counter is recalculated to % value by Zabbix | 
+| **docker.dev[fci,cfile,cmetric]** | IO metrics | cfile - container blkio pseudo-file, e.g.:*blkio.io_merged, blkio.io_queued, blkio.io_service_bytes, blkio.io_serviced, blkio.io_service_time, blkio.io_wait_time, blkio.sectors, blkio.time, blkio.avg_queue_size, blkio.idle_time, blkio.dequeue, ...* Some pseudo metric files are available only if kernel config *CONFIG_DEBUG_BLK_CGROUP=y*.<br>, cmetric - any available blkio metric in selected pseudo-file, e.g.: *Total*, option only for selected block device is also available e.g. *'8:0 Sync'* (quotes must be used in key parameter in this case) |
 | **docker.up[fci]** | Running state check | 1 if container is running, otherwise 0 |
 Doc: https://docs.docker.com/articles/runmetrics/