Add documents and samples to sbk-charts

[kmgowda]

Describe the Issue (Bug/Feature)
sbk-charts the python application to process SBK results.
here is quick start guide : https://github.com/kmgowda/SBK#sbk-charts

To Reproduce
Refer to these links : https://github.com/kmgowda/SBK#sbk-charts and https://github.com/kmgowda/SBK/blob/master/sbk-charts.md
run the SBK with -csv option on any supported drivers ; get the performance numbers in csv file
use the csv file of SBK command to sbk-charts application to create the xlsx files with graphs

Expected behavior
Add more documentation and samples here: https://github.com/kmgowda/SBK/tree/master/samples/charts

Additional context
Add more excel file or improve the documentation of skb-charts
sample xlsx documents are here: https://github.com/kmgowda/SBK/blob/master/samples/charts/sbk-file-read.xlsx