[JIRA] (OVIRT-2025) Document STDCI "V1.5" poll upstream sources jobs

Document STDCI "V1.5" poll upstream sources jobs ------------------------------------------------ Key: OVIRT-2025 URL: https://ovirt-jira.atlassian.net/browse/OVIRT-2025 Project: oVirt - virtualization made easy Issue Type: Task Components: Documentation, Standard CI (Pipelines), STDCI DSL Reporter: Daniel Belenky Assignee: infra Since we're about to introduce pipeline based poll-upstream-sources jobs, we need to have documentation for the process. Docs should include: # How to create such job for a given project: implement a JJB temlpate # How to configure STDCI configuration file so poll-upstream-sources will work. If anything else is needed to be documented regarding this feature, please add it as a comment.