Update description to be exposed in the Plugin Manager UI view

[v1v]

It shows The Jenkins Plugins Parent POM Project, see below:

Let's use the short description from https://plugins.jenkins.io/workflow-durable-task-step

[dwnusbaum]

Seems like a good idea to me, but I wonder if there was any reason this was not done previously? Looks like most Pipeline plugins are missing descriptions, for example workflow-cps and workflow-job.

If it wasn't an oversight, perhaps the reason is that workflow-aggregator has a description, and at the time the various plugins we have today were split from the aggregator the idea was that everyone would only interact with the aggregator plugin in the UI?

[v1v]

Indeed. I've found a bunch of plugins which don't have that particular description. So I took the lead to raise this PR rather than asking more widely in the mailing list. It sounds reasonable the reason for using the aggregator as the main interaction, but it's also awkward to skip the description by default. In both cases, I do not have any strong opinion. Let's see what others think about it.

Thanks @dwnusbaum