[Bug] Doco update

[gmisura]

https://mitre.github.io/saf-training/courses/advanced/11.html#updating-the-workflow-file says

saf validate threshold -i results/pipeline_run_attested.json -F threshold.yml

Yet when I try it i'm told -F doesn't exist

saf validate threshold -i ec2-al2023_inspec-result_post.json -F threshold.yml 
 ›   Warning: Nonexistent flag: -F
 ›   See more help with -F threshold.yml -h or --help

I see it should be -T

Looks like the local doco is correct: https://github.com/mitre/saf?tab=readme-ov-file#thresholds