[RFE] Append self-scheduled assignments with a configurable prefix in description

[sadsfae]

This RFE would cover automatically pre-pending self-sheduled assignment descriptions with a configurable description: e.g.

/opt/quads/conf/selfservice.yml

ssm_description_prefix: "[SSM]"

[sjug]

ygg https://review.gerrithub.io/c/redhat-performance/quads/+/1216500

[sadsfae]

This is implemented.