Clarify where issues are to be reported.

[jtnord]

There is a component in JIRA and there is the github issues.
There should be one source of issues (well ok 2, one is the source code :) )

[jglick]

https://issues.jenkins.io/issues/?jql=component%20%3D%20parallel-test-executor-plugin%20and%20resolution%20%3D%20Unresolved specifically.