H5: Minor fixes

exercises/h5.md

@@ -541,7 +541,7 @@ Check also
 
 **Observation period:** 24.-26.02.2018
 
-NOTE! Average values are not visible in the attached picture!
+**NOTE:** Average values are not visible in the attached picture!
 
 | Field | Description | Average |
 |-------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------|
@@ -602,7 +602,7 @@ It may not be wise to collect Swap statistics (although Linux kernel [Swappiness
 
 ------------------------------------------------
 
-### I/O statistics
+### SAR - I/O statistics
 
 ![sar-iostat](https://github.com/Fincer/linux_server_setup/blob/master/images/sar-iostats.png)