README broken hyperlink

[harvey-intel]

Metric is linked to https://github.com/intel/lpot/blob/master/docs/metrics.md instead of https://github.com/intel/lpot/blob/master/docs/metric.md (the actual url)

[ftian1]

thanks for raising that. we will fix asap

[hshen14]

Thanks for reporting the issue. Fixed now. Closing this issue.